After going back to work my breast milk supply has gone down and I can't feed him enough since the daycare is asking me to add another 4oz bottle each day.

I'm trying to start adding the extra bottle as formula instead. I have tried twice so far and both times my baby (4 month old) just has a complete meltdown when I put it in his mouth. He absolutely hates it. So far I have tried Similac. I have enfamil as well I can try but haven't yet (received tons of free samples in the mail). I have tried to give it to him when he's hungry but not yet fussy. I have tried to add a little bit of my milk to help make it taste more like me.

I know it might take him a little bit of time to get used to the formula but has anyone gone through this and have any tips?