Our ped recommended the same thing. I tried the drops and the baby only screamed. I tried maybe 2-3 times. Then I realized it was futile to put something in her mouth when she didn't know how to swallow. I asked another ped in the same office and he said it doesn't matter if I only do it when I remember. So I totally put it aside and intentionally forgot about it.
I also got advice from the La Leche League who said that my breastmilk offered the best vitamins, et al, that my baby needs. My little one is 21 months now, but I remember those early weeks.
I'm sorry I just realized you are using formula. Read the labels--don't they have the same vitamins?