Scribing Lines for the first time

I scribe on top of the lines.

Part of the answer may depend on who's method and what tools you're using... it may be hard to keep a knife or needle on one of those ridges, but I use a scribing tool that carves out a pretty good, though perhaps too large, gouge.

I just re-scribed a good portion of my P-40 fuselage. I read somewhere else in the forum about using Dymo tape, used for making labels as a straight edge. The hard edge to pull the tool against edge and adhesive back to hold it in place worked like a dream. I have the scriber that cuts out a little hair of plastic as you draw it across. I have never tries to go over a raise line before but I would go right over top using the Dymo and scriber. If you set it just right it should take out the raised and leave the engraved. If you miss it a bit try a light buff with a green Scotch Brite scouring pad then wet 600 grit sand. You may need to lightly go over the scribes again with the tool just to clean them up.

The Dymo works great, guys....it gives a nice "shoulder to lean on" so to speak..

Cheers

Gb

Read this article - should go a long ways towards helping you out.
http://www.swannysmodels.com/Scribing.html