You can customize product page by heading towards:
Dashboard >> Appearance >> Customize >> Reign Dokan >> Product Page
Show Vendor Header – Allows you to show vendor header on top of the product page.
Show Vendor’s Products Section – Allows you to show vendor’s products on the product page.
Number Of Products – Allows you to select a number of products to show in the vendor’s products section.
Show “Sold By” Info – Allows you to show “Sold By” information in product meta information section on the product page.