I'm currently skiing on a RS-1 66" with Radar Rail front boot and rtp. The Rail boot is a good 1/2 to 3/4inch thick on the foot bed where the rtp is basically a thin bit of rubber probably 1/4inch thick.
Correct me if I am wrong, but with this difference I would always be putting more weight on the front of the ski to keep balance ?
Should I raise the rtp so it is level or more the binding backwards ?
I would say you would probably be putting more weight on your back foot as a result of the front boot being raised higher than your back toe plate. I thought the radar rail toe plate had a pretty sizeable pad underneath it as well. Raising your back boot would be pretty good... lowering your front might be better. Either way, without seeing you ski, I would imagine you might have to move your boots forward in order to balance this out.
I believe Radar has two different style toe plates... the one that looks more like a "slipper" has the bigger pad, which would make it more compatible/ complimentary w/ the Rail boot. The latest 2010 version (ARTP) of which has laces and offers a far more customizable fit IMHO.