The ribs are done with front post double crochet.
here's a tutorial:
the buckle looks like two sc rows crocheted directly to the hat starting at one corner of the brim hat and then extended & changed to double crochet with a buckle attached. or there could just have been a color change for the last two rows, with a double crochet band sewn on one side.
If you still need help getting a full pattern, just let me know and I might be able to work something out.
Edit: I just remember a pattern similar to that picture except the hat in that pic. is done with bulky yarn and this pattern uses a much smaller yarn weight so it will come out differently. Here it is nonetheless. http://mimi.csa.googlepages.com/freepattern-warmcapwithbrim If you are a ravelry member you can see how other people's versions look like.