OK.... I only just saw this post today, so I'm over a year late in leaving a response. But just in case others look at this for help in resolving their own similiar issue, I had to provide the correct solution! This has NOTHING to do with Adobe Acrobat AND you don't need to acquire any extra or special software. What you want is very doable and very easy. Keep in mind that creating pdf files are like creating "print" files. So, whatever your print copy will look like, that's what your pdf will be produced of. In PowerPoint with your presentation open, go to Print Preview. From the top menu, change the Print What drop-down to "Handouts (4 slides per page)". You may also want to check your view % to ensure it's on 100% and the Options to be sure you're saving out in color. Now just click Print, and select your pdf distiller/driver. Bingo....done! You should now have a 15 page, 4 slides per page pdf version of the presentation.