I would give her enough so you feel food in her crop, then put her to bed, taking care to help maybe prop her up on a rolled up towel or something.
I would worry about her aspirating since she's bent over so much, so tomorrow, I'd give frequent small amounts of food/water, allowing for her to digest some in between.
General rule of thumb for juvenile chickens is to feed 10% of their body weight several times a day, but you want to make sure their crop is emptying some in between. Often the crop is very slow when a bird is not well, so you'll have to take that into consideration and adjust amounts and times given.
Hope that makes sense.
It's good that she's able to eat a little on her own. Do you best to get fluids into her. Some folks also give a bit of melon, cucumber or tomato to help with hydration. Not sure if that's possible but something else to think about as well.