replace /etc/X11/kb/spitz.xmodmap with spitz-df.xmodmap and restart X or run xmodmap /etc/X11/kb/spitz.xmodmap
this is not entirely clear to me.
Is the -df file used, or the non-df file?
As for shifting all the other characters to make space for the Umlauts:
To make that easier for climber I append the xmodmap file I use for the weeXpc system, which contains a lot of often used international characters. It has the Umlauts and probably everything else a German user may usually need.
Also, appended is the overview over the key assignments, free assignable key combinations etc.
Climber, just download the akita.zip, unzip it and rename the .xmodmap file to the correct naming for pdaXii13 (-df, non-df...?), then it should work I think (except Meanie modified the codes used in rc.xml to trigger the actions of the application keys etc.)
daniel