Each state has its own requirements for creating a codicil. Some require two witnesses, some three, some a notary. Please consult with your attorney about what best meets your needs.
In all other respects I ratify and confirm all of the provision of my said last Will and Testament dated on the _________ day of ______________, 201_.
IN WITNESS WHEREOF, I sign, publish and declare this instrument to be a Codicil to my last Will and Testament in the presence of the persons witnessing said Codicil at my request this _____ day of ___________, 201__.