All custom patterns must be added to a custom pattern set, even if you've created only one pattern. Custom pattern sets belong to one of the four categories: Single, Double, Drumline, or Drumkit. When you have finished creating or editing a custom pattern, use the file management menu (folder icon, on the top right navigation bar) to add the pattern to a new set, or to an existing custom set of the same category if a such a set already exists. A newly-created and saved custom pattern is immediately available for use on the Tap screen. All custom patterns are accessed from the Custom menu option at the top of the Tap screen.
Once created, custom pattern sets can be exported and saved outside of Rhythm Lab. To do this, use the Share action item (square with up-arrow icon, top right of navigation bar on the Custom screen) to open the "Export Custom Set" feature. You can then navigate through to the custom set you wish to export. Once you've given a name for your file, Rhythm Lab will open the system sharing interface menu and present all of the saving/sharing options available on your iPad. Custom pattern set files are created with the .rlpf (Rhythm Lab Pattern File) extension.