Your question is not clear, what are you trying to do? install RT from your computer iTunes to your iPhone? or from your iPhone iTunes app? there are several ways to get RT into your iPhone and one of the easiest way if to buy a RT from iTunes, you can also look for Rigntones maker in the app store and use it to create your ringtone. I"m sure that several topics are already discussing and providing tutorial about how to get RT into your iPhone, just perform a search and i'm sure you will find what you are looking for.