The issue you are observing is related to a Silverlight limitation which prevents fonts from being embedded in the generated PDF. For this reason not all Unicode characters are exported correctly to PDF and unfortunately we haven't found a solution for this problem.
What I could suggest as a workaround is to try exporting your documents server-side using the WPF version of RadRichTextBox where the mentioned limitation is not present.
I hope this helps!
TRY TELERIK'S NEWEST PRODUCT - EQATEC APPLICATION ANALYTICS for SILVERLIGHT.
Learn what features your users use (or don't use) in your application. Know your audience. Target it better. Develop wisely.
Sign up for Free application insights >>