How to display a node field value in a template file?
Duplicate node.tpl.php and rename it node--article.tpl.php and then it's just:

print render($content['field_custom_field']);


If you really want to stay on the page level you better use page--node--article.php and then you need to get hold of the $node object first somehow. Maybe take a look at Clive's answer here: https://drupal.stackexchange.com/a/32310/15055