Power Point allows you to free form your text anyway you like. For most of my lectures that require APA citations I include them in the body of the slides. For example I will include the following in the slide.
The face of application development is changing due to the inability and lack of effectiveness in incorporationg security technologies post production(Smetters & Grinter, 2002)
At the end of the presentation I will make sure I have a single slide that has a complete APA Reference list of all citations that were mentioned on each slide
Smetters, D & Grinter, R. (2002). Moving from the Design of Usable Security Technologies to the Design of Useful Secure Applications, New Security Paradigms Workshop, ACM, 2002.