For in-text referencing within a PowerPoint presentation, add an in-text citation (eg. author, year, page number) next the the point you are referencing. So you might have multiple citations on the one slide if you are referencing more than one resource. Alternatively, if all of the points on your slide relate to one resource, you can add your in-text citation at the bottom right hand corner of the slide. Make sure you add all of the references used throughout your presentation as a full Reference List on the last slide.