Noah's proposed solution works, but I was able to get the screenshot functionality to work on iOS as well by modifying the part of FeedbackForm.cs where the screenshot gets captured. It turns out Application.CaptureScreenshot() uses a different path on iOS than on other platforms, as documented here: http://answers.unity3d.com/questions/339335/ios-app-using-applicationcapturescre.... I added a couple of preprocessor directives that modified the path when on iOS, and the form worked as intended.
Hope this is helpful!