My baby has acid reflux. i don't know what kind of formula is best to use?

May not help much: There isn't a formula that is best for reflux...But some may be more agreeable to the baby than others. Elemental formulas are somewhat easier to digest--such as nutramigen/alimentum etc..--but can be quite expensive. Keep baby head elevated after feeding, thickening forumula with rice cereal etc..May help. If not adequate, see your doc for possible treatment etc..Congrats and good luck..