Only distributions of otherwise taxable funds in an IRA can be a QCD. Since a qualified distribution from a Roth IRA is never taxable, it is not permitted to be reported as a QCD. Instead it must be reported on Schedule A as a charitable contribution, the same as if the distribution was paid to you and you then wrote a check to the charity.
It's extremely rare that any distribution from a Roth IRA could qualify as a QCD. It would have to be a distribution made from a Roth IRA after the participant reached age 70½ but before the 5-year qualification period has been met, and the IRA has investment gains. The QCD is not permitted to exceed those investment gains.
