Configuring ClusterSSH to Use Freetype Fonts

I have read the question [cluster-ssh: specify terminal font](https://unix.stackexchange.com/q/230106/10489) and confirmed that my configuration works fine with valid non-Freetype font names as passed to, e.g., xfontsel. However, I would like to use Freetype fonts instead. With urxvt I specify my font as xft:Source Code Pro:size=9 in my X resources; the same specification works fine when given directly with the -fn command line option. However, if I use the same specification with the -f option to cssh or the terminal_font setting in .clusterssh/config I get an error message: Fatal: Unrecognised font used (xft:Source Code Pro:size=9). Please amend $HOME/.clusterssh/config with a valid font (see man page). How can I specify this font to ClusterSSH? (For those whom might be helped by a look at the source code, the error originates in the get_font_size() function of /usr/share/perl5/App/ClusterSSH.pm on my system; I suspect it's the $xdisplay->QueryFont($font); call that's failing.)