Supplements..........which one??????

ok so I have a 4 year old quarter horse gelding that I show in showmanship, western pleasure, horsemanship, and trail. I'll also show in halter but only at the smaller shows because my horse just isn't a halter horse. I want to put him on a supplement but when I got online to originally buy a weight gaining supplement I then got overwhelmed and couldn't decide what supplement I wanted. My horse isn't gross skinny or even really skinny at all. He's not fat either. But I would like to put some meat on his bones because during the mid summer we're hitting shows every weekend and our riding schedule is hard and he sweats off his fat and I feel like a bad owner when I'm walking around a skinny horse. He gets fed properly I just ride off more calories than what he's getting. But then I saw muscle building supplements and hoof supplements too. I want all of these. I want my horse to have good healthy hooves and at a ideal weight with some muscle on him because he does look kind of wimpy for a quarter horse. What should I do? Do they make like a all-in-1 supplement?