I have a supplier that rather annoyingly has put PDF links into all their descriptions - but not the full hyperlink just the /blah/file/help.pdf so I now have 5000 missing links as these are attaching themselves to my domain and being crawled and I think this is one of the reasons google has suddenly tanked my rankings.

So I want to stop any links to pdf's being crawled on my site... is it right to add in this in my robots.txt file?

Disallow: /*.pdf$

Is that enough? Many thanks.