By Brandy McDonnell Features Writer bmcdonnell@oklahoman.comRichie Rayfield puts an eerie rasp into his voice as he utters one of the most familiar lines in horror-movie history. “They're coming to get you, Barbara,” the actor intones ominously. “Oh, that's creepy,” says director Kory Kight-Pagala, listening intently as Rayfield, playing the role of Johnny, teases Corrynn Englerth, playing Johnny's sister Barbara as the siblings make a fateful visit to a country graveyard. Although they were participating in the first read-through for Oklahoma City Theatre Company's new production of “Night of the Living Dead,” the terrifying thrills of George A.