Well, if you only run ostarine for 4 weeks you don't really need a PCT, as suppression will be minimal... you could get away with a test booster...
However, I would not recommend running it only 4 weeks... if you want to put on some size, I would go with LGD-4033 for 12 weeks.. something like this:
Weeks 1-12
LGD-4033 10mg per day
Weeks 13-16
Clomid 50/25/25/25
GW 20mg per day