Babies generally get all the nutrition they need with formula. If your baby is breastfed, the Dietitians of Canada, Health Canada and the Canadian Paediatric Society recommend giving her a vitamin D supplement, as breast milk typically has very low levels of this nutrient. What's more, newborns don't get sun exposure like adults do, to produce vitamin D naturally.
If your breastfed baby is born premature, or with low birth weight, or has low iron stores at birth, you may also need to give her an iron supplement. Ask your doctor or dietitian about what supplement is right for your baby.