I wouldn't supplement a puppy's food unless there is a known deficiency. Otherwise you risk creating an excess, and that can be worse. Puppies don't necessarily shed excess vitamins and minerals as adults usually do, and in the case of things like calcium, excesses are dangerous.
As for how much: if it's an adult formula, at this age you can give her about 1.5 times the amount recommended for an adult dog of her weight. Actually, if you read the feeding instructions on any puppy food bag, you'll find that that's pretty much exactly what they do
A baby puppy needs approximately double the amount an adult of the same weight would get. And that multiplyer gradually reduces as the puppy grows (not the actual amount of food, since she'll be moving up the weight ranges during this time, just the multiplyer of the adult amount for her weight) until around 6-7 months, she's eating the same amount, or only slightly more, as recommended for an adult. So at 8 weeks a puppy is getting 2 x the adult amount, at 4 months about 1.5 times, and at 6-7 months just the same amount as recommended for an adult.