1. Usually I recommend parents lend money to children instead of simply gifting. This way if the child got married and later divorced or died, the money can be returned instead of being taken by the child's spouse.
2. However, for a loan to be approved, the downpayment cannot be borrowed, but gifted. There has to be a gift letter stating the money transfer is a gift.
3. So you should use unified credit to gift the money to the child and report it on IRS form 709. This way you avoid gift tax for any amount under 11 million for single parent and 22 million for two parents.