Description: 
Add possibility for adding a type of annotations that can be inserted in the document in order to make their content read only.

Resolution: 
The Read Only Ranges and Document Protection feature is added in the new version of the control. Please use the RadRichTextEditor instead the RadRichTextBox. 
Please refer to our documentation for more information on the following link: http://www.telerik.com/help/winforms/richtexteditor-features-read-only-ranges.html and http://www.telerik.com/help/winforms/richtexteditor-features-document-protection.html