putting the code there is why your conditional test was returning false: the variable $i isn't set until the loop a few lines further down...
You'll need to run the whole logic loop there to see if one of your options is size:

try this:
Code:
<?php if ($zv_display_select_option > 0) { ?>
<h5 id="attribsOptionsText">
<?php
    for($i=0;$i<sizeof($options_name);$i++) {
       if ($options[$i] == 'Size') {
?>
 <!-- bof Popup Size Help 2/2k7/07 -->
<a href="javascript:popupSizeHelp('http://www.ktnaturals.com/catalog/includes/extra_datafiles/sizehelp.html')"><img src="http://www.ktnaturals.com/catalog/includes/templates/custom/images/icons/help.gif" alt="Size Help"></a>
<!-- eof Popup Size Help -->
<?php 
    }
  }
?>
<?php echo TEXT_PRODUCT_OPTIONS; ?></h5>