On iPhones (iOS/Apple) the NFC-antenna is on the back of your phone at the top. If you want to read your patch, place the top edge of the back of your iPhone on the patch.
On Android phones the position of the NFC-antenna depends on the manufacturer of the device. Most of the time, the NFC-antenna can be found near the camera or in the middle at the back.
When you want to read your patch, place your phone over the raised part of the patch and hold it steadily in place. It is important to position the NFC-antenna in the middle of the patch.
Example: For Samsung devices the NFC-antenna can be found in the middle at the back.