Just tested and this seems to do the trick for me (Opens a doc in LibreOffice Writer)
In KAlarm
File > New > New Command Alarm (or use Ctrl+C)
On the
Alarm Tab Tick the "Enter a script" box (the area below it will expand)
Now enter
#!/bin/bash
cd /path/to/your/document/
libreoffice -writer name-of-your-document.odf
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Under the
Time section add the time/date options to suit.
On the
Recurrence tab set the options for daily/weekly etc etc
Press OK (there is an Try button which will test if your script works)
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The screenshot below may help a little
