Kinda tricky, but from the permalink of the questions [
https://meta.superuser.com/questions/1625/how-do-i-view-the-markdown-source-for-a-post ] replace
questions with posts and replace the part after the number ( ie,
So the link becomes https://meta.superuser.com/posts/1625/revisions
So, in general,
For answers, the concept remains the same, except you'll have to replace in the above link with the post number for the answer, which is the number appended after the question.
So, this answer link is How do I view the markdown source for a post?
To get the revisions view, the link is https://meta.superuser.com/posts/1627/revisions
Once you get the revisions view just click on
AFAIR, the view source link was available only on Revisions view - which is available on a single click if the question/answer has been edited.
For others, the above link will open the revisions view and you can select the source from there.