How do you set a Rethyo watch?
If it is the same watch as mine the winder is at the 3 o'clock
position - the key has a double "keyway" on it. Insert as if to
wind normally, push down and turn clockwise - you'll feel the
keyway lock in. Then using some force, pull the key outwards and
you can now set the time. (You can only go clockwise or the keyway
unlatches)