Carbide Create uses the outline font support for Windows/Mac OS (so supports .otf or .ttf files), so true single line fonts aren’t an option (and if one selects a single line font in Windows such as Modern or Roman no text will be shown).
A work-around is:
Or, one can set the text using a special tool such as the “Hershey Font” plug-in for Inkscape, export as a DXF or SVG, import that, and then cut as a No offset Contour.