Any art experts? R F King etching/Loch Etive, need help with valuation/info!?

I have an etching signed in pencil, 1 of 100 limited edition of Loch Etive in Argyllshire, Scotland. Have trawled the internet and can find nothing about him or possible value of this piece of art. Any information would be truly appreciated. It looks at least 100 years old.