You can use the reference circuit or refer to the application note for design.

・Designed with reference to the reference circuit
Reference circuits for switching regulator products are introduced on the ROHM website.
　　Switching regulator reference circuit

・Design based on the application note
Application notes that explain the selection of peripheral components and PCB layout methods in an easy-to-understand manner are available from the ROHM website.
　　Buck Converter IC Capacitor Calculation
　　Buck Converter IC Inductor Calculation
　　Quick reference table for resistor values for setting the output voltage of a buck converter IC
　　About thermal resistance
　　Buck Converter PCB Layout Techniques
　　Precautions for Multilayer Ceramic Capacitors Used in Buck Converters