Those are big dogs!! One can't really say whether the weights are correct or not because it would depend very much on the height of the dog. One can only say that 120 lbs is waaay over the standard, but for the height of that dog, it may very well be correct and the dog is just big! Usually Ridgebacks are finished growing upward by about a year after that it is putting on muscle and filling out, but your breeder knows the line better and the growth of different lines vary a lot. A rule of thumb is that you should be able to see the shadow of the ribs when they move, but never be able to actually put your fingers between the ribs. If you can't see the ribs at all, then your dog is too fat. Hope this helps.
By the way, I used to feed Blue Buffalo but switched a couple of weeks ago because the protein was too high. I ended up with California Natural Lamb and Rice (21 percent protein) and my puppy is doing great; he gets four cups a day plus a spoon of yogurt and a little cottage cheese a couple of times a week. I supplement with 1000 mgs of Ester C and some fish oil, plus a multi vitamin. He's 18 weeks and weighs around 45 lbs. But he is going to be a tall dog judging by the size of his knuckles, tail and ears!
Caroline