This one should help you out. This RC is the easiest in the MKX game. This guy is my 3rd main for teleportation stuff. TG Raiden has the hardest as fuck RC.
Try doing this combo:
21xxFireball, then hold the 1, and then immediately do the RC (meaning the RUN input instead of the Dash cancel in the move list).
Practice this combo making it more faster as you're practicing all the inputs in one string.
edit: set the opponent AI to autoblock. This will help you out of knowing if you're doing it right or not. If he blocks, then that means that you're doing it wrong.
Good luck.