I’ve used another one that was a syringe and needed a lot that went into her bottle or directly into her mouth and she did not like that and didn’t digest it well
D drops! It's so much easier than the syringes
I take a vitamin d supplement of 5000iu that gets into the breast milk if you are breast feeding/pumping.
We use Enfamil® D Vi Sol® Vitamin D Drops per recommendation from our pediatrician
I started with Mommy’s Bliss then used the samples from doctor (Baby D Drops)