The elongation of primed DNA templates by DNA polymerase delta and epsilon requires the action of the accessory proteins PCNA and activator 1. Heteropentamer of subunits rfc1, rfc2, rfc3, rfc4 and rfc5 that forms a complex (RFC) with PCNA in the presence of ATP. Two other complexes exist where rfc1 can be replaced by either ctf18 or elg1 to form the ctf18-RFC or the elg1-RFC complexes respectively. Belongs to the activator 1 small subunits family.