Both methods for including LaTeX formulas in Inkscape (Extensions->Render->LaTeX or extension textext) are using
pstoedit to convert the LaTeX output to SVG. Therefore, I assume that the glyph outlines are extracted and converting them to vector path expressions instead of using characters from text fonts (Inkscape is a vector graphics program, not a text program). As result, the final PDF file will not contain any fonts.
(Disclaimer: I could not test properly, because the installed versions of
ghostscript did not work together and failed.)
An alternative to embed LaTeX formulas with fonts is the following procedure:
- Creating a LaTeX file (e.g. with class
standalone) and the formula.
- Conversion to PDF via LuaLaTeX, pdfLaTeX, ...
- Install the TeX fonts so that Inkscape knows them.
- Import the PDF file in Inkscape.
- When the figure is saved as PDF in Inkscape, use text output option "Embed fonts" and do not use "Convert text to paths".