This seems more like an issue between Excel and PDF than with Report Builder... I don't know much about sending Report Builder reports as PDFs, normally I just send as Excel Files, not PDFs, but I think that PDF files would render the text as actual text, not an image of the text.
When you say broken, what do you mean? Is the text completely missing? Is it garbled? Is it just coming through as a default sans-serif font instead of the chosen font? Is it broken just for the recipients or everyone (as in, could that font be missing or corrupted on the recipient's machine)? Have you tried a different, more universal font (something that is more likely to work on more machines)?
