How to create PDFs from Mac PowerPoint
PowerPoint X under Mac OS X can make PDF files without any additional software.
For OS 10.2+ only:
Go to File, Print, choose the options you'd like, then click the "Save as PDF" button at the bottom of the Print dialog.
For OS X (any version):
Go to File, Print, choose the options you'd like, then click on the third pop-up menu to change from "Copies & Pages" to "Output Options". When you get there, check the "Save as File" button, and choose PDF. Now, just press Print.
Alternatively, in the Print dialog box, you can click on Preview, which will open your PowerPoint presentation up in print preview mode within the Preview application. From there, you can go to File, Save As to save the contents of the print preview as a PDF file.
PowerPoint 2001 and earlier
If you have an earlier Mac OS version or run an earlier version of PowerPoint in Classic mode under OS X, you'll need additional software to make PDFs from PowerPoint.
You can use Adobe Acrobat or one of the lower-cost Acrobat alternatives listed on our PDF/PostScript FAQ