Responsive DP Child Theme _header

I can see how to create child themes by copying the template folder and making changes to the new template theme directory. Modifying the css gives most of what is needed. I do have a question though about making further modifications to the layout in general or more specific to the header. I was able to use pbk-mega-menu in the past instead of the built in menu for Directory Press. I would like to do the same with the Responsive Directory Press but make the changes in the child theme and not to the main themes files. How does one create the _header.php file for the child theme. I don’t see the template file in the original theme and copying the header.php file causes errors.

Is this possible?

Thanks for any assistance.
Tom