Applescripts for Keynote 5.3 (iWork '09), Keynote 6.2 (April 2014 version), Keynote 7.0 (September 2016), and Keynote 10 (Big Sur, January 2021) to semi-automate the process of converting presentations to PDFs.
They use the print dialog rather than the Export... menu item to give more flexibility in the layout etc. I've tried to comment the scripts so that the selections can be easily customized. They stop once the Save... dialog is open, so you can change the filename before saving if desired. Written because of the annoyance of converting my slides to PDF for upload after every class.