The "Embed fonts" option will always embed all fonts in the document. I don't understand what you mean with "a different font" - the idea of embedding fonts is to make sure that whoever receives the document will be able to view/print it with all fonts available, regardless of which fonts they have installed on their system or their printer.
Fonts get embedded either fully (the whole font is embedded in the file), or subset embedded, in which case only those glyphs that are actually used in your document get embedded.
When you execute this profile, it will ask you for a filename to save your new PDF as - the one that contains the embedded fonts. It will leave your original file untouched.
So again, this profile will embed all the fonts that are used in your document. If you want only a subset of fonts embedded, you need to embed them all at first, and then you can unembed the ones that you don't want using the "Save as Optimized PDF" option.
If you want more control over which fonts get embedded you need to look into a 3rd party preflight tool like e.g. Enfocus PitStop.