  We present results from a study of subtractive renormalization of the fermion
propagator Dyson-Schwinger equation (DSE) in massive strong-coupling quenched
QED$_4$. Results are compared for three different fermion-photon proper vertex
{\it Ans\"{a}tze\/}: bare $\gamma^\mu$, minimal Ball-Chiu, and
Curtis-Pennington. The procedure is straightforward to implement and
numerically stable. This is the first study in which this technique is used and
it should prove useful in future DSE studies, whenever renormalization is
required in numerical work.
