I'd avoid using Edwal No-Scratch on the emulsion side in contact printing. It might transfer to the paper and interfere with development. If the scratches are deep enough to penetrate the emulsion, Edwal No-Scratch wouldn't help, anyhow. Such scratches would have to be filled in with something like a very soft graphite pencil, or the marks bleached and spotted in the print. If the scratches don't penetrate the image on the negative, first try contacting them to see if they really hurt. If they do, one possibility when printing onto silver-gelatine paper is to thoroughly wet both paper and negative and press them together with no bubbles. This might best be done in a tray of water. Then contact print as usual. Because, unlike No-Scratch, the index of refraction of water is somewhat different than the index of refraction of film or gelatine, this might not completely eliminate the scratches.