Simply go to the blog, open the source code of the blog and looking for the link you want to check for no follow or do follow. If the link is in the form of <a href=http://www.example.com>Anchor text</a> it is a do follow blog and if it is in the form <a href="http://www.example.com" rel="nofollow">Anchor Text</a> it is a no follow link.
Remember, a web page can have a mix of no follow and do follow links so you can check for a particular link.