Hello PFMC84,
Welcome to Apple Support Communities!
If we understand your post correctly, you are inquiring about how to sync a custom ringtone from your Mac to your iPhone. We're happy to help!
If you created a custom ringtone in an app, like Garageband, you can sync it to your iPhone, iPad, or iPod touch using iTunes for Windows or the Finder on a Mac.
- Connect your iPhone, iPad, or iPod touch to your computer.
- On a PC, open iTunes for Windows. On a Mac, open the Finder.
- Drag and drop the ringtone to your device.
More information about tones and ringtones can be found here: Use tones and ringtones with your iPhone, iPad, or iPod touch"
Let us know if you have any questions.
Thank you for using Apple Support Communities.
Take care!