If you are actually using the Articles module, this should do it:
themes/default/PortalArticles.template.php
<div class="sp_article_extra">
<a href="', $article['href'], '">', $txt['sp_read_more'], '</a> | <a href="', $article['href'], '#sp_view_comments">', $txt['sp_write_comment'], '</a>
</div>
If you are using Board News block, which some people call articles, this should do it:
sources/subs/PortalBlocks.subs.php
<div class="righttext">', $news['link'], ' ', $news['new_comment'], '</div>
cough You are a SimplePortal developer yourself, if I may remind you.