If you support Creative Commons copyright licensing, you can use this as a footer:

<style>

.footer {
	margin: 0;
	text-align: left;
	color: #686868;
	font-style: italic;
	font-size: 85%;
}

.footer img {
	float: left;
	padding: 0 5px 20px 0;
	margin: 3px 5px 20px 0;
}

</style>

<p class="footer"><span><a href="http://creativecommons.org/licenses/by/3.0/us/"><img src="http://i.creativecommons.org/l/by/3.0/us/88x31.png" alt="Creative Commons License"></a></span>This work, excluding any content linked via another source/website, is licensed under a <a href="http://creativecommons.org/licenses/by/3.0/us/">Creative Commons Attribution 3.0 United States License</a>. Permission to reprint in whole or in part is gladly granted, provided full credit is given and references the URL: <a href="#">URL goes here</a></p>

It would look like this:

This work, excluding any content linked via another source/website, is licensed under a Creative Commons Attribution 3.0 United States License. Permission to reprint in whole or in part is gladly granted, provided full credit is given and references the URL: URL goes here