I want to use TuneSmith on both my Windows PC and Mac. How can I synchronize my song catalog?

You can move TuneSmith's backup folder in your 'Documents' folder from one computer to the other.
To transfer changes made on a Windows PC to a Mac, create a new backup on the PC and copy the entire folder to your Mac to replace the existing backup folder. Start TuneSmith on your Mac and choose 'revert' in the backup dialog. This will import any new data from the backup folder and revert any matching records that are already present.
Records that only exist in the Mac version of TuneSmith but not in the backup folder will remain unaffected. Please note, however, that customized pop-up menus of entry fields will not be automatically updated during the import of a previously created backup. These pop-up menus may be updated manually after the import is complete by clicking on the appropriate field label while holding the control (Ctrl) key.