For anyone who gets stuck with this, I managed to figure it out myself.
I downloaded the following add-on
https://plugins.smyl.es/wp-job-manager-field-editor/
This add-on enables you to create custom drop-down lists on the job submission page. Once you have created your list, you can reference the short-code.
Hello,
I have just downloaded the field editor from Myles:
https://plugins.smyl.es/wp-job-manager-field-editor/
you can create drop-down menus with it
