Save to PDF
To save to PDF, all you need to do is press the 'Save PDF' button in the toolbar. This will create one document with all of your Harness or System information.
PDF Settings
You can configure which outputs you wan to include with your 'Save PDF' export. To do this, you can click the arrow next to 'Save PDF' and then select 'PDF Settings...'
This opens the Manage Pages dialog, where you can select which pages you want to generate as well as configure their order. You can also add your own pages to the PDF; see Custom Pages.