Hello Vuyiswa Maseko,
I have prepared a small demo illustrating how you can bind the content of RadRichTextBox using HtmlDataProvider. Note that the ViewModel does not implement INotifyPropertyChanged and two-way binding will not work, but if you implement it, everything should work OK. (The contents of the file cannot be automatically changed, due to Silverlight Security policy with regard to file opening and saving.)
If you want to use RadRichTextBox with RIA services, there is a sample project in the last post of this forum thread. Take a look at it for starters, and if you are not able to adapt it for your project, you can send a demo, so that we can help you further.
If that does not answer your question, do not hesitate to contact us again.
the Telerik team
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