The plugin works with some themes and not others. Just added a new theme and the plugin insists that:
There appears to be an error in calling the Skimlinks Plugin from your theme's footer.php file, please ensure your footer.php file includes the standard WordPress function "wp_footer()" above the closing body tag.
however the end of footer.php on this site is:
<?php wp_footer(); ?>
Would be nice if it works consistently.