Hello,
I'm afraid I am having a hard time understanding your setup and the issue you are facing.
The internalization feature provided by RadRichTextBox's spellchecking functionality depends on the current culture, i.e. in order to make sure the added by you English / British dictionary is used you can specify the current culture:
Alternatively you can specify the spellchecking culture of a specific control spell checker like this:
Please let me know if I misunderstood you or you need further assistance.
Regards,
Petya
Telerik
Check out Telerik Analytics, the service which allows developers to discover app usage patterns, analyze user data, log exceptions, solve problems and profile application performance at run time.
Watch the videos and start improving your app based on facts, not hunches.