1lb of a ration balancer, plus hay/grass for weight, is actually pretty perfect, if that keeps his weight good. Slightly ribby is totally ok in any horse, but especially a 2-3yo. A light cover of the ribs is also fine. If you’re seeing front ribs, that’s a bit too thin but not horrible, and in a 2yo it might be a growth stage and the same calories might cover those ribs in a month.
Also, depending on the ration balancer, you might be able to feed 2lb a day if he needs a bump in calories. Or, as I really like to do, add a cup or so of alfalfa pellets to keep in the mix, and then you can bump to a couple of pounds without having to wean onto it, when he needs a boost, then you can drop back down when he doesn’t. I really like doing that (or beet pulp) because the extra volume when soaked makes it really easy to mix in most supplements. I just soak it all anyway because I think all horses should be ok eating wet food for a lot of reasons.
. Well, nothing too exciting to share yet (I wish I’d got a picture of him checking himself out in the arena mirror!) but here he is hanging out and making friends in his new pasture. 
