Sarah, I use macstitch as well (it's the only software available to us mac users). "Export to pdf" works fine for me.
If you export your patterns as a pdf of "used area only" it generates a smaller file and fits to a single page (well, 3 pages: preview of finished, pattern in blocks/symbols, and key). This is great, unless it's a big pattern that is unreadable as a single page. In that case I export as pdf using entire pattern, and it will cut it to multiple pages at an easily readable size.
I have had the occasional customer unable to open these pdf files (maybe 10 customers in over 650 sales), in which case I pasted each page of the pdf file into a word document and emailed it to them that way.