  If the $X(3872)$ is a weakly bound charm-meson molecule, it can be produced
in $e^+ e^-$ annihilation by the creation of $D^{*0} \bar D^{*0}$ from a
virtual photon followed by the rescattering of the P-wave charm-meson pair into
the $X$ and a photon. A triangle singularity produces a narrow peak in the
cross section for $e^+ e^- \to X \gamma$ 2.2 MeV above the $D^{*0}
\bar{D}^{*0}$ threshold. We predict the normalized cross section in the region
of the peak. We show that the absorptive contribution to the cross section for
$e^+ e^- \to D^{*0} \bar D^{*0} \to X \gamma$, which was calculated previously
by Dubynskiy and Voloshin, does not give a good approximation to the peak from
the triangle singularity.
