Keynote is better than Powerpoint
Keynote file compatability
Unfortunately, you will have to export your Keynote presentation as a Powerpoint file. To do that, click on “File” → “Export To” → “Powerpoint”. If you do not care about transitions and animations, it is even faster to export to PDF and upload the PDF instead.
I understand that this is not the easiest option, but, unfortunately, there is currently no way to import a Keynote file into the Powerpoint to convert it.
Excel File commented
So my workaround on this is to export the the Keynote presentation to a movie. This creates a .m4v file. You can then use the Quicktime app (or others I'm sure) to convert to a .mov file that Yodeck can handle. If Yodeck could handle a .m4v format directly that would remove that last step.
Might want to post that has a help document.