To do Alt + H + I + R on Mac in PowerPoint, download and install Accelerator Keys, then press Option, followed by H, I, then R.
Command: Reuse Slides
This is how to do Alt + H + I + R on Mac in PowerPoint with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with PowerPoint.
Alt + H + I + R opens the Reuse Slides panel, allowing you to browse and insert slides from another PowerPoint presentation. You can preview slides before inserting them and choose whether to keep the source formatting or apply the current presentation’s theme.