I am glad to hear that you managed to resolve the problem.
On a side note, as to your question about the ContentUrl property - indeed, that is exactly what it does - it creates an IFRAME and puts it into the RadPane. After that this IFRAME is resized automatically along with the pane without the need of custom code. You say, however, that you are not sure how to implement it - all you should do is to simply remove your iframe and related to it code and set the ContentUrl to the same page you used to have in your iframe.
In case you have additional questions, do not hesitate to contact us again.
the Telerik team
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