Answer by Heath GM for Blogger template syntax (Label RSS feeds)

OK thanks for the attention everyone ;)

I've figured it out:

<a expr:href='data:blog.homepageUrl +&quot;feeds/posts/default/-/&quot; + data:label.name'><img src='http://2.bp.blogspot.com/-XqVwdzsG73g/T9A44Jq3OPI/AAAAAAAAAA0/RTd9pAVWy9s/s1600/rss-icon.gif' style='vertical-align:middle;'/></a>

Fairly simple: it just involved building the url for each label being specified by the 'data:label.name' bit in the url.

Cheers