Hi Gary.
The problem is, when saving a .pdf vector file, not only on Keynote but on any vector software, the text is not transformed as a outline traced vectors.
If a PC don't have that specific font that was created the .pdf file, it substitutes that font on that .pdf file, for another one. Basically the problem is this: http://www.graphic-design-employment.com/adobe-illustrator-how-to-convert.html
On Adobe Illustrator software, there is a command that converts the Text to Outlines, and far I know Keynote doesn't has that command.
Far I know, the only solution is to use a vector software that does that. I just downloaded the trial version of "Affinity Designer" and probably I will stay with this software.