Part of a membrane-bound complex that couples electron transfer with translocation of ions across the membrane. Couples electron transfer from reduced ferredoxin to NAD(+) with electrogenic movement of Na(+) out of the cell. Involved in caffeate respiration. H(+) + Na(+)(in) + NAD(+) + 2 reduced [2Fe-2S]-[ferredoxin] = Na(+)(out) + NADH + 2 oxidized [2Fe-2S]-[ferredoxin] The complex is composed of six subunits: RnfA, RnfB, RnfC, RnfD, RnfE and RnfG. Belongs to the NqrB/RnfD family.