Keynote
You can show rulers to help you position and align objects, and hide the rulers when you don’t need them.
Click in the toolbar, then choose Show Rulers or Hide Rulers.
When you adjust a unit setting for rulers, it applies to all presentations. You can change the preference at any time, even if you have a presentation open.
Choose Keynote > Settings (from the Keynote menu at the top of your screen), then click Rulers at the top of the settings window.
Click the Ruler Units pop-up menu, then choose an increment (Points, Centimeters, or Inches).
To show the ruler marks as a percentage of the slide, select the “Display ruler units as percentage” checkbox.
You can place 0 (zero) at the center of the ruler, which means ruler units increase to the left and right.
Choose Keynote > Settings (from the Keynote menu at the top of your screen), then click Rulers at the top of the settings window.
Select the “Place origin at center of ruler” checkbox.
Choose Keynote > Settings (from the Keynote menu at the top of your screen), then click Rulers at the top of the settings window.
Select the “Show size and position when moving objects” checkbox.