Hi, 
I would like to make a visualforce page with a preview of the file attached to the Knowledge article within a custom file field.

Currently I am able to do that, but only for an chatterFile/Attachment but not a file-field file, with the code below.
But how to I modify my code to preview a file stored within a custom-file-field on a Knowledge Article

<div class="chatterFileViewerPanel" id="chatterFileViewerPanel">
<embed src="/_swf/192001/sfc/flex/DocViewer.swf" 
    flashvars="shepherd_prefix=/sfc/servlet.shepherd&v={!myDocument.id}&mode=chatterfilepreview&in_tests=false" 
    width="100%" height="100%"  align="middle" id="renditionLarge" quality="high" bgcolor="#f3f3f3" name="renditionLarge" 
    allowscriptaccess="sameDomain" allowfullscreen="true" pluginspage="http://www.adobe.com/go/getflashplayer" wmode="opaque" 
    type="application/x-shockwave-flash" />
<noembed>&lt;p&gt;Flash file preview&lt;/p&gt;</noembed>
</div>
<script>
  insertFlexComponent('/_swf/192001/sfc/flex/DocViewer', 
     'shepherd_prefix=/sfc/servlet.shepherd&v={!myDocument.id}&mode=chatterfilepreview&in_tests=false', 
     '100%', '100%', '#f3f3f3', 'chatterFileViewerPanel', 'renditionLarge', false, 
     { adobeFlashVersionLbl : 'You must enable or download Adobe Flash Player version 9.0.115 or later to use this feature.', 
       downloadAdobeLbl : 'Download Adobe Flash Player', 
       downloadAdobeLinkLbl : 'Click the link below to download the Adobe Flash Player:', 
       closeDialogLbl : 'Cancel'}); 
Ninja.Flex.ContentStaticResourcesBase = '/_swf/192001/sfc';
Ninja.Flex.ShepherdController = '/sfc/servlet.shepherd';
</script>