You can invite buddies to join Hole19 from 2 places within the App:
1. After tapping on the Follow Icon in top-left of the Feed or your Profile, you will see a Invite Buddies Button on the 4th tab;
2. After tapping on the 'More' button (3 dots) on the bottom menu bar, scroll down, and select Invite Friends.
You will then have the option to invite via SMS, Email, Twitter, Facebook, and more.