Making a page in landscape format isn't currently totally intuitive, so here's how it's done:

The key is to just double-click on the background i.e. the page itself (or just single click if the Inspector is already open). The Inspector window will show you page options, one of which is "Page size".

Just select "Custom" from the drop down list...

notice that the Apply button is not enabled by default

...and you'll get a window popup prompting you for the page size you want:


To make it landscape just flip the 2 values, or enter any page size you want - although remember it might come out odd if you try to print a super wide page!

You can see here that when you change the selection in the Page Size drop down list then the Apply button becomes enabled - and the size details just below the drop down list is italicised to indicate this isn't yet the current page size as it hasn't been applied yet.


Pressing Apply disables the button and sets the size details to normal:


And of course changes the page layout!