Subcutaneous RFID would be much less obtrusive and more feasible, assuming you could find a reader. And however you store it on your body, you should also encrypt it with a passphrase that you can memorize.

Maybe subcutaneous micro-sd card, with some sort of medical-grade coating? It would be a serious bitch to get out (any doctor or veterinarian could probably help you there) but once you did you wouldn't have any trouble reading it.