You might be able to adjust the prongs to allow your fletching to clear, you may also have to play with arrow nock rotation. Another option as stated above is to shoot an offset fletch or you may even want to go to feathers since they are more forgiving.

Prong rests can shoot helical but you often have to play with them. They are much easier to work with if you are shooting aluminums such as a 2317, 2413, or 2512. These shafts really allow you to adjust the prongs. With carbons it takes a bit more time & tuning.