F4 F5 F6 Install - Cidfont F1 F2 F3
When a PDF is created without fully embedding the font, the viewing software looks for a local equivalent. If it can't find one, it displays these technical names or throws an "F1 Not Found" error.
Use pdffonts -subst to see actual substitution. Then force substitution via Ghostscript’s -sSubstFont=... . cidfont f1 f2 f3 f4 f5 f6 install
