The fat added to infant formula is usually a blend of vegetable oils. Here is the ingredient label for an Enfamil product, Neuro Pro. I have put in bold the fats. Also, you will see lecithin in there as one of the ingredients. Lecithin functions as an emulsifier to prevent the fats from clumping.
Nonfat milk, lactose, vegetable oil (palm olein, coconut, …