Waralan,
Congratulations on finding some possibilities.
Without tracing the ancestors of these Rutters, to see if they converge with your Rutters, there is no sure way to see if they are related to you.
I would say that a letter would be fine, people will not think you are tactless, if they are interested in their genealogy they will be thrilled to hear from you. If they aren't interested in their roots they will just think you are a little eccentric, and the English like eccentrics in general.
If I was traced by an American cousin, no matter how distant, I would be thrilled and excited to receive a letter from him.
It would be better to hand-write rather than print a letter though, as in the past there have been some scams from people offering to trace American relatives and you would not want to be confused with them.
Kazza.
