Potential activity points are earned every 2 weeks that you are active. That means, for every 2 week period, you have to post at least one post to get 14 activity points. Your post has to be higher or equal to the potential activity for it to show.

For example, if i post 15 post in 2 weeks, I will gain 14 activity. If i post one post in that two week, and 28 post in that period after, I will gain 28  activity post that week.