How do add the handicap calculator? 30. July 2017 adrian (0) Access the Add-Ons, scroll down to the "Single Items" section and click the "Handicap Calculator" row. Details about the purchase along with screenshots will be provided on the right side of the screen. When you are ready to purchase, click the "Buy" button in the upper right corner of the screen and follow the In-App purchase instruction provided by Apple to complete the purchase.