Which GPIO pin would i put a radio extender on

I have a Raspberry pi 2 Model B and ive found this pifm thing and now want to broadcast strange things over my sisters station! But after running script it dosent reach far enough so i looked online but all i could find is tut for Rpi original. I made an antenna out of some tin foil and wire but which gpio pin do i attach it to.

Any help would be nice

Thanks


-Liam