keynote > preferences > ruler > ruler units: use inches or centimeters
this allows you to draw, position text and objects accuratly for printing
file > page setup > paper size A4, scale 100%
this allows print settings to match Kenote and choose the correct paper orientation
file > print > print
sends the file to the printer and allows what to print:
slides, notes or handouts
include builds, background, slide numbers
Keynote layouts are done in Pixels, but to get a presentation to print 'nicely' on A4 paper you need to make sure you set the pixel dimensions of your page to match the dimension ratio of A4 paper (i.e. 1:1.41421356237). Choose any other ratio for your presentation (e.g. 1024x768) and when you try and print, to get the images onto the A4 page the printer process will have to shrink your slide - you'll end up with 'wide' side margins.
You can use any pixel size that has the right dimension ratio, but two you might want to consider are:
- 842x595 - this will produce files that when imported into Powerpoint are interpreted as "A4" documents
- 2048x1448 - the largest size that will fit cleanly (i.e. without scaling) on a Retina iPad screen.
Whatever pixel size you choose, OS X print system will scale the image to print neatly on an A4 page.