Only active players can add-on. (Eliminated players can re-buy, and inactive players can buy-in.)
You can perform an add-on for one player at a time, or multiple players at the same time.
Add-on For a Single Player
1. To perform an add-on for one player, tap the player, then in the popup menu tap Add-on:
2. Edit the Chips and Cost if necessary, then tap Do It!
3. You'll notice the player info shows the additional chips and cost:
Add-on For Multiple Players
1. Tap the Players button:
2. Tap Add-on:
3. Tap the players you want to perform and add-on for:
(Note, to select or deselect all players, tap the box in the upper right.)
4. Edit the Chips and Cost if necessary, then tap Do It!
5. You'll notice that each player's info has been updated with the additional chips and cost values: