You are obligated to pay the reasonable cost of repairs for damage that you caused. Turn the claim over to your auto insurance carrier and let them handle it.
***This response is provided solely for general information purposes and is not intended as legal advice, nor does it create an attorney-client relationship.
You are responsible for the "reasonable" repair costs to fix the door. Sometimes a door can't be fixed, the dent can't be taken out and the door skin has to be replaced. Turn in over to your insurance company and don't worry about it. Most of the time you can't just paint a repair, you have to blend the pain to match the door. Sometimes you have to completely repaint the door.
You are responsible for the reasonable cost to repair the damages, plus loss of use damages during the period of repair. The owner of the vehicle should obtain several estimates for the cost to repair the damages caused by the person who hit the door. The repair of the damage and the blending of the paint is not considered an extra. You can turn the matter over to your insurance company for adjustment. Your insurance company will likely prepare an estimate for the damages.
You are required to pay for any damages that are a result of your door hitting the car. Normally when something like this happens, the entire door has to be painted to make sure everything matches. So this would be part of the damages you caused.
I am licensed in Pennsylvania. This post is not legal advice, but instead contains general educational information. Please do not act or refrain from acting based upon what you read in this post. Also please remember that this post does not form an attorney/client relationship between you and me. If you have specific legal questions, you should contact an attorney in your state for assistance.