Puppy doesnt eat as much as the tin says he should!

We are feeding our puppy Gizmo on butchers choice puppy with tripe as this is what the breeder had him on. On the tin it says how much he should have to be divided over 4 feeds but he just doesnt eat that much, he is a tiny 8 1/2 week old yorkie. Otherwise, he is happy, mental, pooing and weeing fine, tail wagging, training, sleeping etc. This happened when I had my daughter she only drank the tiniest amounts of milk and now age 11 has always been a small eater. Does the same rule apply with puppies? as long as theyre eating something thats better than nothing?