OpenTable Payments is currently available for iPhone users running iOS 7 or higher. Encourage these users to visit pay.opentable.com from their iPhone, and then follow the instructions onscreen for set up.
Viewing the Check - Guest Experience
When a guest uses Payments during their dining experience, they will get notifications of the updated check each time the server adds a new item to the bill.
If the guest does not allow push notifications on their iPhone, they will need to manually launch the OpenTable mobile app to view the check. Unfortunately, it is not possible for the OpenTable app to override the personal settings on a guest's iPhone.