Rebuild the document in PowerPoint. There’s no way to do a one-step conversion. You could save the PDF as a JPG (or a series of JPGs if it’s multipage) and insert each JPG into each PPT slide. You can’t insert a PDF directly. Note that this will lose the editable text in the PDF making your PPT non-WAG compliant; you will need to add back content to make the document accessible. Easier would be to present the PDF in full-page mode, as you would the PPT. If you need handouts, the PDF will give you better control over your prints.
I use after: (for Mac, I’ll try to get the latest version of after to work). You will need to install the after build of this page. The following links should help. The following links should help.