Lighting in RenderMan is flexible but also very straightforward for users.
RenderMan includes a set of basic geometric lights, built-in. These specialized shapes - Domelight, Distantlight, Rectlight, and Spherelight (particularly the latter two) - can provide superior sampling behavior, compared with arbitrary geometry (i.e. standard geometric primitives with a light Bxdf attached). There's also a Portal Light to improve lighting interior scenes lit indirectly through openings like windows and skylights.
Note that due to these optimizations, the spherelight requires that all scale transforms be uniform, e. g. X,Y, and Z scale must all be the same so as not to skew the sphere shape into an ellipse or other form.