OS X 10.11.6
Only happened first time I chose "Large Tex: Larger".
KM9 quit unexpectedly.
I cannot duplicate this. Please send the crash report to support@stairways.com
It would be in the ~/Library/Logs/DiagnosticReports folder
You can get to ~/Library in the Finder by holding down the shift (or option) key and selecting Library from the Go menu in the Finder.