As per the Moderator comment on your other thread, you're still posting your finds in the wrong place.
Nevertheless, if this is the same fork as in your other thread, it's by the Whiting Manufacturing Company in their "Adam" sterling silver pattern, introduced in 1907. Their manufacturing base was in New York at this time.
The "R.G. Winter" on the back will likely be the name of a retail jeweller for whom Whiting custom-produced the item as part of a cutlery range. It might be the "R.G. Winter Jewelry Company" of Minneapolis. I don't know the company history, but they had a listing in the 1915 city directory.