Engraving letters in Windows means always engraving two lines along the outside of a letter coz Windows doesn't have or support single line fonts. Single line fonts consist of one line along what would be in a TT-font the centerline of the letter.

Now creating such single line fonts manual is a lot of work.

MillWrite V8 (http://www.hugequestions.com/MillWrite/index.html) offers help with some commands to create such fonts. With a few mouse clicks (for each letter) and some manual corrections you'll have a single line toolpath to engrave.

Milling this font with a 30°, 45° or 60° tapered tool will make it look like handengraved.