Why are you thinking of supplementing?
There are definitely reasons to do so, but every situation is different.
For me, I had a premature baby who weighed only 4.9lbs, so he had formula within an hour of birth and was supplemented with it until I could produce enough milk for his 8 feedings a day needed to gain weight. We also had breats feeding challenges due to his early arrival and tongue tie, so at first he was getting formula plus expressed breast milk. Thsi was all done under teh care of his doctors and a LC, as my goal was to move him to exclusive breastfeeding. As I was able to produce more milk (due to a crazy pumping schedule) we gradually cut down on formula. He is 10 weeks now and hasn't had any formula in 6 weeks. At teh end he was just getting one bottle a day.
Remember, that for any formula you give you have to pump to keep up your milk supply. I'd suggest consulting with a LC if you can.
BFP#1 11/12/11 ~ No heartbeat 12/12/11 ~ D&C 12/19/11
BFP#2 3/25/12 ~ Heartbeat 141 4/16/12 ~ No heartbeat 4/25/12 ~ D&C 04/30/12 BFP#3 7/16/12 ~ EDD 3/26/13 ~ It's a BOY ~ DOB 2/26/13
DD 12/20/99, DS 12/14/12, M/C 9/2014, M/C 1/2015