I purchased a ringtone and it does not show up in my selections to be able to set it as my ringtone.

Hello there, jkort23!

Thanks for reaching out to the Apple Support Communities! It sounds like you're having an issue downloading and using a purchased ringtone on your device. If you have followed the steps in the article Use tones and ringtones with your iPhone, iPad, or iPod touch, inluding the steps for redownloading and have checked to by sure you don't need to Update your iPhone, iPad, or iPod touch, we would recommend reaching out to Apple directly by checking out this link to Get Support and they will be more than happy to proceed with additional steps.

Cheers!