“Interactive” could reach a new level at the Richmond Shepard Theatre on East 26th Street during the run of “Rent Boy: The Musical.” The show, which plays through next Sunday, was produced in association with rentboy.com, the biggest source for male escorts worldwide. An advertisement for the show, directed by David Leddick, a photographer of male nudes, promises, “Everyone on stage is for $ale!” And the show has even partnered with the Hookies, the International Escort Awards.