If I understand you right, you want to load files in Rich Text Format (RTF) in RadRichTextBox. This is possible for the first time with the latest version of our suite - Q1 2011, which should be available for download in your account any time now.
The sample code is as follows:
RadRichTextBox supports different file formats (including Docx, HTML, RTF), and there are help articles that can help you to start using them - about our format providers
and data providers
Don't hesitate to contact us if I misunderstand you or if you have other questions.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!