QCD support: there is no explicit support for this kind of tax-free withdraw from the qualified funds. You could take withdraws and make corresponding special expenses or payments to charity, but you'd have to provide a special receipt to pay yourself back the taxes incurred, and that would need to be calculated on the side.
Or you could remove the amount you intend to use in the QCD from the balance of your IRA and simply leave that amount out of the equation. This prevents the taxable event and it leaves the correct balance in your qualified account, but this approach might undermine your purpose in the QCD if that purpose is related to satisfying some RMD requirements.