I would like to add a custom form inside the <field name="arch" type="xml"> tag that submits data to a remote site like below. Is it as easy as just adding html or is there a special way this needs to be done?

<form action="http://www.site.com/remote-service.php" method="POST" target="_new" id="remote-form"> 
 <input type="text" name="keyval">
</div>
</form>