The Custom Fields section, found under Appearance > Theme Options > Custom Fields, allows you to enable the following 5 settings on your site: Custom Javascript, Custom CSS, Real Post Author, Page Permissions, and Post URL overwrite.
The Theme Options' Custom Fields section
Custom Javascript
Enable the option to place custom javascript on individual pages and posts. Once enabled, a custom text box will apear on page and post write panels and the custom javascript will be written in the footer of the HTML document.
Custom CSS
Enable the option to place custom CSS on individual pages and posts. Once enabled, a custom text box will apear on page and post write panels and the custom CSS will be written in the head of the HTML document.
Real Post Author
Enable the option to credit the real author of a post or page without having the author be a member of the site.
Page Permissions
Enabling page permissions will allow you to display content only to a more targeted audience, based on their user level.
Post URL overwrite
Enable the option to redirect pages and posts to a different URL once their URL is displayed.
