They don't usually put hairball prevention ingredients in kitten food. Kittens don't actually spend as much time grooming and cause themselves to swallow the hair the way adults do. But if she seems like she is doing a lot of grooming, you can give her Laxatone. It's a paste that comes in a tube. You just smear a little on her lips or paw and she will lick it off. Once she is an adult, various brands do make hairball formulas. I am starting to transition my oldest (11 months) to Royal Canin Persian furmula. It is a special formula designed for their specific needs. My kitten food is Royal Canin kitten. Persians/Himalayans have smaller mouths and sometimes have a hard time with larger kibble. Royal Canin even makes a Babycat formula for kittens under 4 months that is really small kibble. You can see all their products including a picture of the size of the pieces on their website.
When having long-haired cat you can help her with grooming, if possible on daily basis. Get a comb in the pet store and brush her. It will reduce amount of hair swallowed as well improve a bond with your cat. Laxatone is is a good idea as it was mentioned and also soft food helps smooth evacuation from GIT. You can get kitten sotf food.