This option doesn’t seem to work on the camera tag but it works in the render settings.
C4D R16 A6 latest build
Bump because of another user report.
I did not manage to get custom shape bokeh working, at least not any colored bitmap. An example of this is producing fake chromatic aberrations, as explained at the very bottom here: https://coronarenderer.freshdesk.com/support/solutions/articles/5000516203