That Nook webpage seems quite specific.
- The directory you need to create and copy the Liberation fonts into (if you haven't already) is /my fonts (all lowercase and including the space) and it needs to be created in the same place as /my documents
- The magic Nook url is
Code:
src: url('res:///system/media/sdcard/my fonts/LiberationSerif-Regular.ttf')
Pay particular attention to the quotes wrapped around the url location. Did you make sure you had this? The Sony url doesn't need them but I suspect the Nook does because of the space in the path between my and fonts
P.S. Did the fully embedded epub work on your reader?