There is a demo of a MS Word-like use of the rich text box together with the ribbon at http://demos.telerik.com/silverlight/beta/#RichTextBox/MSWord. You can view the code used for creating the demo by clicking "View code" in the top-right corner. This example is also included in the sample projects which are included in the installation zips. You can download it from your account.
Import from and export to doc are currently not supported and have not been scheduled, i.e. it has yet to be determined if and when they will be implemented. For a list of the available file formats, you can refer to this help article.
If we can help you with anything else, do not hesitate to get back to us.

Please find attached a stand-alone MsWord example of the rich text box for Silverlight. It pretty much copies the code from the examples, included in the installation for Q1 2011 (2011.1.315).
As for dynamically building the content of document, that can be done through RadRichTextBox's and RadDocument's API. This forum thread deals exclusively with code-behind manipulation of the document before it is shown in a rich text box. There is also a small demo in one of the first posts, that can help you get started. Basically, you can manipulate the Children/ Inlines/ Blocks properties of the different document elements before the document is measured and arranged (which happens once the document is shown in the editor). After that, you can use the methods from the API (InsertInline(), Insert(), etc.).

Hi Iva:

Thank you. That was very helpfull. I have used following code to generate document code. But it doesnt seem to render rightly.
Is this approach is correct?

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  RadDocument doc = new RadDocument();
                doc.LayoutMode = DocumentLayoutMode.Paged;

                Telerik.Windows.Documents.Model.Section section = new Telerik.Windows.Documents.Model.Section();
                doc.Sections.Add(section);

                doc.SectionDefaultPageMargin = new Telerik.Windows.Documents.Layout.Padding(50, 50, 50, 50);

                ///Build To Address
                Telerik.Windows.Documents.Model.Paragraph paragraph = new Telerik.Windows.Documents.Model.Paragraph();
                section.Blocks.Add(paragraph);

                Telerik.Windows.Documents.Model.Span spanTo = new Telerik.Windows.Documents.Model.Span();
                spanTo.FontSize = 10;
                spanTo.Text = "To," + "\r\n";
                paragraph.Inlines.Add(spanTo);   
               

                Telerik.Windows.Documents.Model.Span spanRefPhy = new Telerik.Windows.Documents.Model.Span();
                spanRefPhy.FontSize = 10;
                spanRefPhy.Text = referringPhysician + "\r\n";
                paragraph.Inlines.Add(spanRefPhy);  

                Telerik.Windows.Documents.Model.Span orgName = new Telerik.Windows.Documents.Model.Span();
                orgName.FontSize = 10;
                orgName.Text = relatedOrganisationObj.related_organization_name + "\r\n";
                paragraph.Inlines.Add(orgName);            

                Telerik.Windows.Documents.Model.Span addLine1 = new Telerik.Windows.Documents.Model.Span();
                addLine1.FontSize = 10;
                addLine1.Text = relatedOrganisationObj.address_line_1 + "\r\n";
                paragraph.Inlines.Add(addLine1);

                if (relatedOrganisationObj.address_line_2 != null)
                {
                    Telerik.Windows.Documents.Model.Span addLine2 = new Telerik.Windows.Documents.Model.Span();
                    addLine2.FontSize = 10;
                    addLine2.Text = relatedOrganisationObj.address_line_2 + "\r\n";
                    paragraph.Inlines.Add(addLine2);
                }
                if (relatedOrganisationObj.city != null)
                {
                    Telerik.Windows.Documents.Model.Span city = new Telerik.Windows.Documents.Model.Span();
                    city.FontSize = 10;
                    city.Text = relatedOrganisationObj.city +" " + relatedOrganisationObj.state_code + "\r\n";
                    paragraph.Inlines.Add(city);
                }
           
                if (relatedOrganisationObj.zip_code != null)
                {
                    Telerik.Windows.Documents.Model.Span zipCode = new Telerik.Windows.Documents.Model.Span();
                    zipCode.FontSize = 10;
                    zipCode.Text = relatedOrganisationObj.zip_code + "\r\n";
                    paragraph.Inlines.Add(zipCode);
                }
                //End of Build Too Address

                Telerik.Windows.Documents.Model.Span spanFrom = new Telerik.Windows.Documents.Model.Span();
                spanFrom.FontSize = 10;
                spanFrom.Text = "From," + "\r\n";
                paragraph.Inlines.Add(spanFrom);

                Telerik.Windows.Documents.Model.Span docName = new Telerik.Windows.Documents.Model.Span();
                docName.FontSize = 10;
                docName.Text = "Dr." + App.global_user.first_name + App.global_user.last_name + "\r\n";
                paragraph.Inlines.Add(docName);

                Telerik.Windows.Documents.Model.Span orgName2 = new Telerik.Windows.Documents.Model.Span();
                orgName2.FontSize = 10;
                orgName2.Text = facilityObj.facility_name + "\r\n";
                paragraph.Inlines.Add(orgName2);

                Telerik.Windows.Documents.Model.Span addLine12 = new Telerik.Windows.Documents.Model.Span();
                addLine12.FontSize = 10;
                addLine12.Text = facilityObj.address_line_1 + "\r\n";
                paragraph.Inlines.Add(addLine12);

                if (facilityObj.address_line_2 != null)
                {
                    Telerik.Windows.Documents.Model.Span addLine22 = new Telerik.Windows.Documents.Model.Span();
                    addLine22.FontSize = 10;
                    addLine22.Text = facilityObj.address_line_2 + "\r\n";
                    paragraph.Inlines.Add(addLine22);
                }
                if (facilityObj.City != null)
                {
                    Telerik.Windows.Documents.Model.Span city2 = new Telerik.Windows.Documents.Model.Span();
                    city2.FontSize = 10;
                    city2.Text = facilityObj.City + "\r\n";
                    paragraph.Inlines.Add(city2);
                }
                if (facilityObj.state_code != null)
                {
                    Telerik.Windows.Documents.Model.Span stateCode2 = new Telerik.Windows.Documents.Model.Span();
                    stateCode2.FontSize = 10;
                    stateCode2.Text = facilityObj.state_code + "\r\n";
                    paragraph.Inlines.Add(stateCode2);
                }
                if (facilityObj.zip_code != null)
                {
                    Telerik.Windows.Documents.Model.Span zipCode2 = new Telerik.Windows.Documents.Model.Span();
                    zipCode2.FontSize = 10;
                    zipCode2.Text = facilityObj.zip_code + "\r\n";
                    paragraph.Inlines.Add(zipCode2);
                }

                radRichTextBox.Document = doc;