In my non-expert opinion, I think the food should be fine. I checked the Solid Gold website and here is what they say about their small breed formula:
We recommend feeding small breed puppies the Just a WEE BIT formula. It is specifically formulated for smaller breeds which have a higher calorie requirement per pound of body weight than larger dogs and the nutrient profile closely matches that of the Hundchen Flocken puppy formula. Thus, it is suitable for puppies and adults alike.
I didn't know smaller breeds had a higher calorie requirement per pound. Most people here are feeding foods that are not size specific, so I don't see any problem. There isn't anything else different about the formula that I can see, no unusual nutrient ratio or ingredients.