Most sources- his compositions, his arrangements- give only S.N. Penfield, but at least one of his compositions is dedicated to the Savannah Conservatory of Music, which Smith Newell Penfield is apparently known to have founded after leaving Rochester, NY (after having been born in Oberlin) for Savannah, Georgia. Later he resided in New York City. There are always issues of identification when only initials are available (consider James H. Rogers, which attaches to two approximately contemporary early 20th century composers with overlapping genres- songs, for instance - James Hotchkiss Rogers and James Henderson Rogers) - but there seems good reason to assume that S.N. Penfield is Smith Newell.