The process is slightly different depending on whether you're using the Paddle or Mac Appstore version of PeakHour. See How do I tell which distribution of PeakHour I have? if you're unsure.
Ensure PeakHour is not running on either machine whilst you do this.
Direct (Paddle) version
- Copy the file ~/Library/Preferences/com.digitician.peakhour4.plist to the same directory on the target machine.
- Copy the directory ~/Library/Application Support/PeakHour to ~/Library/Application Support on the target machine.
Mac Appstore version
- Copy the directory ~/Library/Containers/com.digitician.peakhour4 to ~/Library/Containers on the target machine.
Once complete, reboot the target Mac. This will ensure any old cached preferences are cleared.