The user was trying to configure their custom field to allow the selection of a HR sub-service under the HR Service field. They wanted to know how to make it function like the Out of Box (OOB) HR Service field does, as their attempt to make the field a "Drop-down" type field did not work (when clicking on the field on the HR form, only the "-- None --" option displayed).

It was found that the user needed to configure their custom "HR Sub-service" field to be of type "Reference" like the OOB HR Service field.

Once this was modified on the corresponding sys_dictionary record, results appeared per the user's expectation.