Addendum to Absorption of a massive scalar field by a charged black hole

In Phys.Rev.D89, 104053 (2014) we studied the absorption cross section of a scalar field of mass $m$ impinging on a static black hole of mass $M$ and charge $Q$. We presented numerical results using the partial-wave method, and analytical results in the high- and low-frequency limit. Our low-frequency approximation was only valid if the (dimensionless) field velocity $v$ exceeds $v_c = 2 pi M m$. In this Addendum we give the complementary result for $v lesssim v_c$, and we consider the possible physical relevance of this regime.