Yes, you can do that. But the b's do have a strong taste, so you'll have to see if she'll eat it. I would mix it with a small amount of something moist, so it sticks to the food, you can use her regular feed mixed in a little water if she'll eat that. Being in molt and not feeling good, she may just be protesting being handled. All the new pinfeathers can be sensitive and uncomfortable and they often don't want to be touched. Sometimes they will start sleeping in nest boxes or under roosts rather than roosting because they don't want to be bumped or touched by others. If the pill didn't come back out, she likely swallowed it. If it's easier you can try wrapping her in a towel, like a burrito to hold her, then pull down on her wattles to open her beak, pop it in. You don't have to push WAY back, just enough that she swallows rather than spitting it out.
