implode.php

// Start UL (Unordered List)
echo "<ul>";

// Get the field value
$amenities = get_custom_field( 'job_amentities' );

// Make sure there is a value
if( ! empty( $amentities ) ){

    // An Array would be multiple selections
    if( is_array( $amentities ) ){
    
        // Loop through each one and output it in a LI (List Item)
        echo "<li>" . implode( "</li><li>", $amentities ) . "</li>";
    
    // One selection would be a single 
    } else {
        echo "<li>" . $amentities . "</li>";
    }

}
echo "</ul>";