I would not give any extra food at this point. Your pup has a month to go, the pup isn't very big at all. Most of the growth is in the third trimester. And with such a small litter, I would wait until the dog has three weeks left, and then I would only give a little extra, 1/4 cup or so, when she cleans her dish and starts looking for more. Do not supplement calcium. Good luck.
Heidi Ho, Odie
Joy-Joy, Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.