The AMA Manual gives no specific guidelines for citing and referencing in PowerPoint presentation slides.
If this is for a class, you should check with the professor to see if he or she has a preference. However, it is generally accepted to include the full citation on each slide instead of including all citations on one slide at the end of the presentation as PowerPoint presentations can be disassembled. You can reduce the size of the citation's font to make it appear less distracting.
Keep in mind that you should definitely give full credit to the sources somewhere in your presentation. Also, be consistent; If you cite one way on one slide, be sure to use the same style throughout the rest of the presentation.
