To embed an SGF simply link to or upload your SGF using the upload icon when creating or editing your forum post. This will create a tag that looks like
<a class="attachment" href="//ogs-forums.s3.amazonaws.com/180fa201ebfff173f271ba8f737f12486e593a6668.sgf">game.sgf</a>
and will show up like this:
game.sgf (2.1 KB)
If you would like to upload a go problem, you can add type="problem" in the tag, like this:
<a class="attachment" type="problem" href="//ogs-forums.s3.amazonaws.com/191dd488eb0fbea50dfbcb95975cc0ef8d80e1591d.sgf">problem.sgf</a>
and it will be displayed as a go problem instead of a full game.
problem.sgf (116 Bytes)