The game page and the various game listings shows a -icon, if there are attached SGFs with game reviews to download. The icon is linked to the page to download the stored SGFs:
On the game page, the icon is shown below the game board to the right of the 'View move'-button and to the left of the 'Comments'-link. The tooltip of the icon shows how many attached SGFs are available.
On the game listings, the icon is shown in the separate column 'Attached SGF'.
To find games with attached SGFs you can use the filter-checkbox in the 'Attached SGF'-column in the game listings. This is possible for all game listings (my/all running/finished/observing/observed games). Please be aware, that some of the game listings have further filter restrictions per default for the end-date.
You can use the following links to find games with attached SGFs (without default end-date restrictions):