To use it put : iconarttradesfriendsonly : without the spaces.
You should get this ~Arttradesfriendsonly (https://www.deviantart.com/arttradesfriendsonly)
Original stamps made by SweetDuke (https://www.deviantart.com/sweetduke)
Stamp set http://dukeofsweethotness.deviantart.com/art/Status-Stamps-Plz-Accounts-174033030