In our online help you can find information about how to replace default MOSS editor
with the RadEditor in List scenarios http://www.telerik.com/help/aspnet-ajax/using-radeditor-in-list-items.html
I think that once you follow the steps described in the article, everything should be working fine.
If you need further assistance, we will be glad to help you.
All the best,
the Telerik team
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