The inheritance pattern of the Rh blood system is autosomal dominant, i.e., the heterozygous manifests as Rh+. The dominance is complete (R is dominant over r). The possible genotypes are RR, Rr (both Rh+) and rr (Rh-).
Curiosity: the Rh factor is codified by a gene containing 2790 DNA nucleotides situated in the human chromosome 1.