Recently I was asked to post a zip file containing the reference html. All zipped up it was just under 2mb which is way above the upload limit of a post. So what I did was put the file in my Dropbox public folder. Then I just posted a link to that file. There is a limited amount of upload space for the forum and Dropbox gives you 2.5GB of online storage free. By using Dropbox or something like it you can post files as large as you want and it is not taking up any forum storage.
Once you have your file stored in the Dropbox public folder, right click on it and copy the link.
Then in the body of your post put the link in like this:
and you get:Reference 5.3.2.zip