We have implemented an option to use custom tags in frames which should help in your case. You can check this article in the documentation for more info: http://docs.telerik.com/teststudio/user-guide/code-samples/html/tagframe.aspx
 Basically using the latest release you should be able to both add a simple tag in the iFrame itself like iframe src="http://www.example.com" testStudioTag="ExampleTag"></iframe> or you dynamically assign tag to iFrame in the code which will be set for the purposes of the running test using myFrame.TagFrame("MyCustomTag");