This is from shipping stress, i would put a tiny bit of sugar in their water, or some liquid chick vitamins, and dip her beak in it a few times. They don't have to drink the first 3 days after hatching, but they are probably at that point. Also, to encourage her to eat more you can tap at the food with your finger, and hold it there. They should all come running, and by holding it there a minute it will encourage them to keep eating, if they have a weak appetite. The most important is the water, though. Otherwise they will not be able to process the food.
She is probably a weaker chick, on account of her size, and will need encouragement the next few days. You can also smush some chick food with spoons, and make a warm mash in the bottom of a pop/milk cap, and dip her into that too. Usually after a few dips they will start to swallow. When her crop is full, you will feel a little soft spot on her top left side as you are looking at her. Just make sure you don't dip her nose holes! One of mine was this way, and is still small, but boy does she zip and outrun the "big guys" now!
