Presenter notes are contained in Presenter Display
To use Presenter Display when Keynote is in Play, two displays are needed
Presenter Display is shown on the local display and the presentation is shown on a projector or large display
1 - Connect a second display to the Mac which is powered on and has the input selected for the Mac
2 - Apple Menu > System Preferences > Displays > Arrangement: deselect mirror option
3 - Keynote Preferences > Slideshow: select the option for; Enable Presenter Display
4 - Select the content and layout of Presenter Display:
* Play > Customise Presenter Display
* Click the layout button within Presenter Display:
5 - If Presenter Display is showing on the wrong display, swap displays by pressing X on the keyboard
6 - If there is only one display available, eg a MacBook, presenter display can be shown using:
Play > Rehearse Slideshow