functions.php

<?php
/**
 * Filter for fields before filtering based on $filter value
 * 
 * Filter syntax is `job_manager_field_editor_get_fields_pre_filter_{$field_group}` ... replace {$field_group} with field group
 * 
 * Job Fields: job_manager_field_editor_get_fields_pre_filter_job
 * Company Fields: job_manager_field_editor_get_fields_pre_filter_company
 * Resume Fields: job_manager_field_editor_get_fields_pre_filter_resume_fields
 *
 * @param   array  $fields      All fields in array structured format, similar to
 *                              'meta_key' => array( 'label' => 'Field Label' ....
 * @param   string $filter      The type of filter that will be used on the fields (all, default, custom, enabled, disabled) after you return them
 */
add_filter( 'job_manager_field_editor_get_fields_pre_filter_job', 'my_custom_options_filter', 10, 2 );

/**
 * Add Custom Options to Field Through Filter
 *
 * This example function adds custom options to a field, but you can use this to set
 * pretty much any field value, or configuration, before it is passed to plugin to output
 * in list table, or to core WP Job Manager (for frontend output, etc).
 *
 * Any changes made here will show up in the List Table GUI where you edit fields.
 *
 * @since 1.4.2
 *
 * @param   array   $fields
 * @param   string  $filter
 *
 * @return  array
 */
function my_custom_options_filter( $fields, $filter ){

	// If our meta key `job_options` does not exist, return all fields
	if( ! isset( $fields['job_options'] ) ) return $fields;

	/**
	 * Set our custom options for the `job_options` meta key field
	 *
	 * Add ~ to the end of the key to set it as a disabled option
	 * Add * to the end of the key to set it as the default selected option
	 *
	 * Options MUST be in the following format:
	 *      array(
	 *          'option_value'  => 'Option Label'
	 *      );
	 *
	 * The value saved to the database (and output on frontend) will only be the key,
	 * the label is ONLY for output of the dropdown, radio, etc.
	 *
	 * In example above, if Option Label is selected by user, option_value is what is saved to db
	 */
	$fields['job_options']['options'] = array(
		'value_disabled~' => 'Disabled Value Label',
		'value_default*' => 'Default Value Label',
		'regular_value' => 'Regular Label'
	);

	return $fields;
}