you can achieve this simply by using the Generic Container control. Generic Container control allows you to insert arbitrary HTML and if you want to streamline this, you can create a snippet. Here is more info on the RadEditor (control inside of GenericContainer) snippets: http://www.telerik.com/help/aspnet-ajax/codesnippets.html
I hope you'll find this information helpful. Let us know if there is anything else we can do for you.
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.