6 month old kitten throwing up

Does anyone know why my 6 month old kitten would be throwing up everytime she eats hard food?

Stop feeding her hard food!

Well how do I stop feeding her hard food when I have 2 other cats that eat hard food and its out all day?

Wet food is much better for kitties in the long run (http://www.catinfo.org/  for why), so would you be willing to consider switching to all wet and timed meals? Here's a thread on how to transition. http://www.thecatsite.com/t/264675/transitioning-free-fed-kibble-kitties-to-timed-meals-and-new-food

If not, then I would feed the kitten wet food separately (in a different room) and keep the kibble in a place where the kitten can't access it. Most likely, there is an ingredient in the dry food that does not agree with the kitten. It's also possible that the kitten eats too fast and is regurgitating it.