The SITI Company presents Radio Macbeth, which tells the story of Orson Welles and his company of actors (Mercury Theatre on the Air) rehearsing for a radio broadcast of Macbeth. As the rehearsal unfolds, the actors become possessed by the play and its spirits of ambition, violence, fortune and fate. Today, Friday, Feb. 4, and Saturday, Feb. 5, at 8 p.m. Clarice Smith Performing Arts Center's Ina and Jack Kay Theatre, University of Maryland, University Boulevard and Stadium Drive. College Park. Tickets are $35. Call 301-405-ARTS or visit claricesmithcenter.umd.edu.