Add Custom Field Key in functions.php

Question

Is there any way to add custom field keys to the dropdown of the custom fields on the "add new post" page without adding the fields?

Answer 1

Check add_meta_box (It allows plugin developers to add sections to the Write Post, Write Page, and Write Link editing pages. ):

http://codex.wordpress.org/Function_Reference/add_meta_box

Or these plugins:

• Custom Field Template: http://wordpress.org/extend/plugins/custom-field-template/
• Flutter: http://flutter.freshout.us/ (this one may be what you are looking for)
• Magic Fields: http://wordpress.org/extend/plugins/magic-fields/

Source: http://sltaylor.co.uk/blog/control-your-own-wordpress-custom-fields/