It sounds like you would need to filter the images table using the fk column and compare it to the value from the article recordset. Something like:
<?php
$rsImages = new WA_MySQLi_RS("rsImages",$connPIW2015_i,0);
$rsImages->setQuery("SELECT images.id, images.fk, images.name FROM images WHERE fk = ?");
$rsImages->bindParam("i", "".($rsArticle->getColumnVal("id")) ."", "-1"); //LoopParam
$rsImages->execute();
?>