If you drop the DF then yes, you will need to feed when he wakes after bedtime (assuming it's at least 3 hours) and later in the night if he wakes and is hungry. You can try to resettle first, but if he's hungry he won't settle for long. I think you either need to carry on giving the DF or stop doing it and leave him to wake when hungry, if you keep stopping and starting it then it will be more unsettling for him. You may find he only wakes the once between bedtime and morning, my two didn't take to the DF and by 12 weeks were only waking once (from what I can remember anyway!).
Laura