Hrm, I'm not using dropbox right now, but I have in the past. I could reconfigure my hfm real quick and make some screenies.
Here you go:
Assuming you have dropbox installed, and a public folder already, go ahead and create a 'folding' sub folder.
Warning: Spoiler! (Click to show)
Set your local path to the dropbox folding dir, you can either copy the whole log, or just the HTML, I just do the HTML.
Then go to your dropbox folder:
Right click, copy public link on 'summary.html', then past it in your browser. That should be your public HFM link, then you can just add it to your sig, or whatever.
Twas the public folder that was holding me back. none of my other folders had the 'copy public link'
EDIT : you're an editor... can't rep... soooo High-Five!