In Logic Pro, click the Save button at the bottom of the Library pane. If the Library is not visible, click the Action menu on the kit controls bar, then choose “Open Library”.
In the Finder window:
Browse to the file location you want to use. The default folder location is User Kit Patches. If required, create a new folder.
Type the kit patch name, then press the Save button.
Logic Pro User Guide: PDF
Logic Pro Effects: PDF