It would be good to examine the bird that was exhibiting symptoms that you saw.
Pills are pretty easy to administer yourself. Just pull down on the wattles and pop the pill inside the beak, let go of the wattles. She'll swallow it unless you have a pill shooter on your hands. So get ready to catch if that's the case.

Practice makes perfect, you'll have the hang of it in no time.
IF you can't figure out which bird, then I would suggest you use a poultry vitamin that goes in the flocks water and do it that way. Look for one that has B1, B2 and E. But I would only give them vitamin water 1-2 times a week, they also need fresh plain water as well.
Hence direct dosing the hen in question is best practice.