When does projectile vomit of a 7 week old become a problem?

My 5 month old always spits up. I will be holding him and all of the sudden I hear a splat on the floor. I guess the big issue would be if it is truly projectile vomit. The Dr told me to cut down the oz fed at the feedings. He said that their bellies only really hold 3 oz and the rest will eventually make it's way up. We are currently on a 4oz every 3-4 hours feeding schedule and have been for a while. I add a small amount of rice cereal to his bottles sometimes and that cuts down on his spitting up. The formulas made for excessive spitting up have rice starch already in them. I can't give you a personal experience with any of them, we use goodstart. My nephew was placed on Similac Sensitive RS (i think that is the name) for his spitting up. Good luck! You know your baby better than anyone so just watch him. We go through A LOT of bibs and outfits too!