Most probably the postback you generate is a partial one, since closing the popup and reloading the RadRating on the page is needed.
If this is your scenario, you can use a RadAjaxManager control in order to trigger the AJAX request and declare the rating on the page as updated control in the settings of RadAjaxManager, which will result in updating the rating when an AJAX request is initiated.
To demonstrate this approach, I created a sample that shows how you can use the selection of the rating in the popup to update the rating on the page. I used a RadWindow instance as a popup, nevertheless you can replace it with a popup of your choosing, which will change only the implementation of the showing and closing of the popup.
I hope this helps. If you are still having difficulties after checking the attached sample, please modify it so that it matches your scenario and send it back. In case this is not possible, you could also describe the changes I need to make to the sample in order to recreate your case more accurately.
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