The instructions below work for Keynote version 10.2 and 10.3. There might be some modifications needed for older versions.
I suggest that you take two simple steps to eliminate two possible sources of confusion. You can reverse these steps once you are comfortable with the proceedure for recording.
• If you use some software that interacts with your computer's sound system, something like "Boom," turn it off. These apps don't always play well with Keynote. IMPORTANT: To avoid wasting time and encountering frustration be sure to check that the microphone you are using is recognized by your Mac. (Hint: If your Mac recognizes your microphone, an indication of sound level will appear, as you speak, in the lower left corner of the record screen described below.) Macs have trouble with microphones that are part of a headset plugged into the headphone jack. You can check by going to System Preferences -> Sound. You may need to make security changes to allow the Mac to access whatever microphone you intend to use. For help in doing this seek solice on the internet.
• If you use two monitors, then disable one during your initial phase of learning how to record. There are many HowTo's to be found on the web, for example. There are also many bells, whistles and adjustments that are not covered here. This is meant to be a minimalist introductory HowTo; it should be all you need.


Fill in the slides -without audio- as if you were going to present them in person, then go to the site at which you can fill in text, insert images, etc. In the "Navigator view" You should see thumbnails of all the slides in the left column. In the upper right hand corner you should see a choice "Format|Animate|Document" Click on "Document."

You should then get a pop-up box with a choice "Document|Audio" at the top. Click on Audio. This will open another pop up, one that looks like a TV screen with a musical symbol in its middle. Click on "Record." When you do this you will see your first slide. At the very bottom of the screen will be the crucial controls. Most important: you will see a red dot. Pushing this will start the recording of whatever input is connected to your computer (most likely the built in microphone, or an external microphone on a headset plugged into the earphone jack of your computer). Push the red button. You with then get a 3-2-1 countdown after which you can start your narration of your first slide. When you are finished with that first slide, press the pause button (two vertical lines).

Next go to the upper left corner and click on the slide navigator to go to slide 2. Hit the red button, then hit it again to get the 3-2-1 indication that you're about to record. Then record the narration for your second slide and continue as with the first slide.

Follow this pattern until you've finished the narration for all your slides then, at the end, after the last narration, click on pause, then click once on the red button, then hit escape. You can check your recording by going to the Toolbar and clicking Play -> Recorded Slideshow. Then save it: File -> Save.

Now you need to make a movie. In the Toolbar, click File -> Export -> Movie. In the popup window then choose Playback: Slideshow Recording and Resolution: 720p. You should now have a file with an extension *.m4v. The size of that file should be reasonably small, for a 12 minute talk it should not be much more than 100MB, perhaps much less. If your m4v file is significantly more, download and use the open source app Handbrake. This is free and fairly transparent.