Hi Rakesh Reddy,
There is a demo of RadRichTextBox and WCF RIA services in this forum thread (the last post).
Data-binding is achieved with the help of data providers - HTML, XAML or the recently introduced RTF. The approach with all of them is pretty much the same, so you should not meet any difficulties adapting the demo to use HtmlDataProvider instead of XamlDataProvider.
the Telerik team