1. Click on "Settings."

2. After that, click on "Custom Fields".

3. Click on "Add Field."

4. Click on "Dropdown (Single)".

5. Review the custom field you selected.

6. After that, click "Next" to proceed.

7. Enter a name in the "Field Name" section.

8. Use the drop-down menu to select a "Group."

9. Enter your preferred option name.

10. Next up, click on "Add an option".

11. To remove an option, click the delete icon next to it.

12. Another drop-down menu will appear for object selection.

13. Click on "Additional Preferences" for further customization.

14. If you require a unique key, click to customize it.

15. Add field description.

16. To wrap up, click on "Save".
