My dog bit her puppie leg by accident?

No, don't put iodine on it or introduce any type of foreign substance to a mother and her new pups unless absolutely necessary. As long as it's not bleeding, she'll be fine. Mom will keep it clean and that will hasten healing. Just keep an eye on it. Females often get a little over zealous when cleaning their newborns, and chew a little more off than they should. The puppy will be fine.