What Era?

As delivered, or later in their life?

As delivered, the RS-1's probably came with either one single chime pointed forward, or a pair of single chime horns, typically one pointed forward, one pointed to the rear.

Later in their service life, the OEM horns could have been replaced by the RR with multi-chime horns.

You'll really need to reference a photo of a C&NW/SOO RS-1 that's the closet to your chosen era.

Andre

As delivered

Era on both CNW and SOO units is 1955-1960.  They both have one chime pointing forward. I'd like to select a compatible sound from the Loksound V5 horn options.

Okay

Now I understand.

You already know the type of horn the prototypes were equipped with (one single chime pointed forward). What you need to know now is what LokSound horn would be the best matching sound.

Andre

Single-Chimes

Single Chime horns tended to be Leslie A125 or A200's. If they were 2-chime, I believe E2's were usually used for that.

I'm doing an RS-3 for the Litchfield & Madison, and was the last RS-3 built. Apparently, their one optional extra was the addition of a Nathan M5.

I found an audio track for

I found an audio track for the different Nathan, Leslie, and Wabco RS-1 horns on the Soundtraxx website. Loksound's website had the audio, but not linked to the type of horn. Anyway, problem solved. Thanks Andre and Juxen.