Select this option to generate Responsive Web Design website. For this option to work, select "Tools" > "Preferences" from the main menu. Select the item "Publish Website" from the list on the left. Deselect the option "Generate Responsive Web Design website". If this option is off, Responsive Web Design websites will not be generated for all websites. Then select this option. RWD website will be generated for this website when previewing and publishing.