Passing variables in URL via. HTML action in PHP with WordPress

I’m looking to pass a variable in a URL as www.example.com/view-job?id=155, however WordPress doesn’t allow this to be done as you’d normally do in PHP.

I have found a function, which is widely used:

function add_custom_query_var($vars){
    $vars[] = "ID";
    return $vars;
}
add_filter( 'query_vars', 'add_custom_query_var' );

And I’m supposed to use it to a link as another page as such:

<?php add_query_arg( 'ID', $job_opening_id, site_url('/view-job/'))?>

The tricky part though, is that $job_opening_id is set in a for loop, and it seems that the action method doesn’t take add_query_arg as an argument. Here’s how I do it:

<? for($i = 0; $i < count($rowArray); $i++) { ?>

    <form method="post" action="<?php add_query_arg('ID', $job_opening_id, site_url('/job-openings/view-job/'))?>">
    <? $job_opening_id = $data->response->result->JobOpenings->row[$i]->FL[0]->content;
}
    <td class="jobopenings-td">
       <input type="hidden" name="job_id" value="<?php echo $job_opening_id ?>" />
       <button id="jobopening-link">
           <? echo $data->response->result->JobOpenings->row[$i]->FL[1]->content; ?>
       </button>
    </td>
    </form>

I’m not quite sure how to go about this. I’m convinced it’s supposed to be a parameter in the action method, as it’s supposed to be redirecting to another page with the variable in its URL.