I have a MacBook Pro with OS X 10.9.4 and Keynote 6.2.2. I have a presentation done in Keynote with slide and music. Now I want add a voice over. Can I do that and if so how?
Go to Play → Record Slideshow and click the Record button at the bottom to begin.
You could also use QuickTime Player to record the audio separately, in case you want to edit it, add pauses, etc. QTP is actually a pretty versatile tool; it can do screencasting and general recording but most people don't even know it's there.