Verify by title that you are displaying the correct PDF.
If necessary, use the key to find the correct file.
Check the article's title (and possibly content) for indication that it
deals only with a workshop, for example, and isn't academic research.
Tick the nonacademic box in this case. If the box is already ticked,
verify the computer's guess.
Check the top right hand corner for a badge and keep an eye
out for possible badges elsewhere. Tick the badge box if found.
Look at the end of the paper, footnotes, and acknowledgements for URLs.
If need be, query the entire paper for general search terms or specific websites.
Paste the URL, along with desription/source if provided.