Where can I find the RSS URL on blogspot?

The answer simplified!

RSS is the address of the most RECENT blog post from your blog. It is NOT the same as your homepage or blog URL. 

For instance my blog address is http://louisewise.blogspot.com but my LATEST post written (the address is usually found when clicked on the post title) is my RSS URL.

Still struggling?

Try adding  /feeds/posts/default?alt=rss after your ordinary blog address.
Example: http://louisewise.blogspot.com/feeds/posts/default?alt=rss