How many cups should i feed my 4 months rottweiler fromm family dog food?

my vet told me recently to try 4 cups a day but i see that my rottweiler is still hungrey how much do you recommend ? i use fromm family large breed golden. And his weight 61lb he's not Fat but he's really a big boy he will be 5 months by Feb, 20. I was feeding him Royle Canin before but he started don't like it so i changed to Fromm Family large breed Goleden. If anyone can help me Please......