  We extend previous work [arXiv:1908.09095] to the case of Maxwell's equations
with a source. Our work shows how to construct a retarded vector potential for
the Maxwell field on the Kerr-Newman background in a radiation gauge. As in our
previous work, the vector potential has a "reconstructed" term obtained from a
Hertz potential solving Teukolsky's equation with a source, and a "correction"
term which is obtainable by a simple integration along outgoing principal null
rays. The singularity structure of our vector potential is discussed in the
case of a point particle source.
