Part of the RFC clamp loader complex which loads the PCNA sliding clamp onto DNA. Heteromultimer composed of small subunits (RfcS) and large subunits (RfcL). This protein undergoes a protein self splicing that involves a post-translational excision of the intervening region (intein) followed by peptide ligation. Belongs to the activator 1 small subunits family. RfcS subfamily.