At first glance, I thought the vertical dots were just
a separator bar, not
an action button.
I don't think a standard "document" icon
is going to work well. Most people
see those and think things like "save" or "new document" or such.
We had been using a "Puzzle Piece" icon to represent an article in various
mockups, but that might not work with the public.
I think someone else suggested this, but what about a
big down arrowhead?
That would correlate with the down arrow in the section headings.
I am also thinking about symbols that imply action, or extending the
reading of the article in some way.
Maybe a tool icon would work. Usually if I can't find some action in an app,
I look under tools. Example: