Using a Heading 1 and redefining the style create the two-inch margin required by Rackham on the chapter titles and major headings like Dedication and Acknowledgments is often the best method.
By adding the extra space above the Heading 1, you combine the one inch margin from the document with the one inch of space on the heading to create your two inches.
Please note that you must have a "Section Break (Next Page)" ahead of your section or chapter heading for the Heading 1 style to insert that additional space. If you're not getting a two inch margin, it's most likely that you're missing the "Section Break (Next Page)".
See Setting Up a Heading 1 Example on the previous page for the step-by-step instructions for modifying your Heading 1 style.