Creatine is one of the few supplements with hundreds of clinical studies backing it's safety and effectiveness. As long as you are using a sensible dosage, it is perfectly fine on your kidneys. The same people who argue that creatine supplementation is hard on your kidney's are the same people who argue that a high protein diet will cause kidney damage. Unless absolutely excessive - both are perfectly safe.
Supplement with 5-10g of creatine per day. I like the creatine supplement ancient strength from n2bm.com. Each serving contains 5g of a creatine blend from three different sources. I take 1 serving pre workout and post workout.