Mac OS X stubbornly displays the incorrect currency symbol for the Swiss franc: Fr. (or sFr. or SFr. depending on your OS version) instead of CHF which is the correct ISO symbol.
This is a problem when invoicing applications rely on system settings to format your numbers. There is an easy fix: edit to your global preferences file to set it right. Unfortunately, it seems to reset periodically (through system updates maybe?).
So for memory, here is the command line to type in Terminal:
defaults write .GlobalPreferences AppleICUNumberSymbols -dict 0 '.' 1 '’' 10 '.' 17 '’' 8 'CHF '
Hopefully, this should be fixed in the upcoming Mac OS 10.7 (Lion).