
I have only a medium size breed and I wouldn't expect them to be adult body weight until around 18 months to two years of gae, otherwise they would be fat.
My young 15 month old is about 90% of her adult weight at 18kg. You cannot really go by food guides too much as even dogs of the same bred sex and ge living similar lifestyle will differ in the amount fo food they require.
You must use your hands and eye. I would want a Mqalamute pup to carry about the same covering as my Elkhounds. Under the coat you should be able to feel the ribs, but not too mcuh backbone. The last ribs should be easily felt and there should be a waist when you stroke back looking from above. If the pup is very ribby and the backbone is proud and you can easily find the Pin bones as you would in a sight hound, then it is too thin. Do not mistake lack of maturity with being too thin. Pups will often look lanky, but still be covered, as it is their structure that still has to mature.
How is his toilet output. A lot can be gauged from the waste as to how well the food is suiting him. If he is loose it could be that he is not digesting the food, or is being overfed. If his droppings can are solid and can be rolled onto a shovel then he is digesting his food well.