Follow these instructions to create a new certificate set for the iOS custom app.
If you select a Wildcard provisioning file to use, you will also need to specify the App ID for the application. In addition, the push notification certificate will not be available in the certificate set. If you select a provisioning profile that already has push notifications configured for use, App ID for the app is already defined and the field will be read-only in the certificate set. However, you will be able to set up a push notification certificate.