When you are viewing an article on the Publications site, there is a "Supporting Information" link presented, if there is any supporting information available for the article.
You will see a "Supporting Information" link to the right of the title in a box under Article Options . The link's location is circled in the image below.
Placing your cursor (hovering) over the Supporting Information link and clicking it will take you to another page that shows the Supporting Information files.
It also offers the following:
a. Viewing the SI files via Figshare
b. Use of magnifying glass to enlarge the files
c. Share functionality
d. Download option