You can find the feeding recommendations on the Hills website. If this is what you are feeding, you can find the feeding recommendations here:
Hill'sŪ Science DietŪ Puppy Small & Toy Breed
For a 5 pound dog, they recommend one cup per day if the dog is less than 4 months old. But a little more won't hurt. In the case of our Bella, like I said, we let her feed freely throughout the day. At 10 weeks of age, puppies are still at risk for hypoglycemia, and need to have food available so their blood sugar doesn't drop.