The files below can all be opened in PageSigner. Make sure to keep the suffix *.pgsg.
You can import them from the menu on the PageSigner button on the Firefox toolbar ("Import").
If the file is invalid, it will fail to import. If it is valid, the html will open (with remote links disabled, so it will usually look very funky). Make sure to choose the option 'View Raw' in the notification bar that pops up; this will show the whole page plus any http headers that were received at the time of notarization. If you find it difficult to see the text that you're trying to verify, just do a Find in that raw version. The raw version is everything that was delivered from the server.
After that, you can also choose 'Manage files' from the button menu; this gives a convenient view of all files you currently have on your system - both those that you generated yourself and those that you've imported (as just mentioned). From there you can rename, export, delete etc. as required and the validation status is also shown.
The file format is binary, you can change its name as you like (but not the suffix as mentioned above).