Yes. liveSite allows you to add "Dynamic Regions" to your System Page Styles for this purpose.
You can also create a Custom Page Style and add your PHP code directly into the Page Style.
For security reasons (to prevent malicious attacks to your website):
1) You cannot add PHP code directly into a text area (page region) using the Rich-tect Editor. If you try, it will be stripped out.
2) You also must first enable Dynamic Regions within your config.php file before you can create Dynamic Regions within the liveSite Control Panel.