121 Domestic and Flag flights are dispatched, 121 Supplemental flights are released. Supplementals are not required (by the regs) to have certificated dispatchers prepare the paperwork. That being said, my last job was with a supplemental carrier and our POI made us put a requirement in our ops manual that the flight followers would have dispatcher certificates. But we still got a "flight release" under 121.597 that meet the requirements of 121.689 v. being dispatched under 121.593 or 121.595 with 121.685 or 121.687 paperwork.