Off Broadway’s Signature Theater has tapped Martha Clarke and Branden Jacobs-Jenkins as the latest additions to its Residency Five program, which promises three full productions to each writer over the course of a five-year residency.Clarke, the choreographer-scribe whose credits include Off Broadway music/theater works “Vienna: Lusthaus,” “Belle Epoque” and “Garden of Earthly Delights,” and Jacobs-Jenkins (“Neighbors”), whose latest play “Appropriate” bows at the Humana Festival in the spring, will each receive a stipend of $50,000 as well as health benefits and additional coin for theater tickets as part of the program. The pair join a Residency Five lineup that already includes Kenneth Lonergan, Annie Baker, Katori Hall, Will Eno and Regina Taylor. Last year Signature presented plays by Hall, Eno and Lonergan through the residency. The Off Broadway company has three stages on which to program works by the residency scribes, slotting them in alongside titles that are part of the theater’s other programming. Signature’s current offering, the well-received revival of “The Piano Lesson,” shutters Sunday.