When you have added your Reddit post, there is a place for a comment as well.
This is an opportunity for yet another backlink.

Click on comment and add your URL from the Reddit that you put in at the beginning of the procedure.
* Note: the format is different than a standard link.
Put your keyword or the text that you would like to display in brackets followed by the URL in parentheses.

Here is an example:

If you forget how you need to format this click on the formatting help link in the bottom Right corner.
This will open a window that shows the format.

When you are finished save your comment.