<? if(CUser::IsAdmin()){?>
    <form name="form1" method="get" action="<?=POST_FORM_ACTION_URI?>">
    <div class="admin-box">
        <? echo FindUserID('CUSTOM_USER',  $arResult['USER_ID'],  "", "form1");?>
        &nbsp;&nbsp;
        <input type="submit" name="search">
    </div>    
    </form>
<?}?>