PostBeyond calculates a user's potential reach by taking the number of followers, friends, and connections in your social media network and multiplying it by the number of posts you have shared during the time when the potential reach was calculated.
Every time a user shares a post, the platform pulls the amount of connections for LinkedIn, Facebook and Twitter. This will amount for the impression the user generates over the configured time you're pulling the data.
For example, if you have 50 Twitter followers one week and share one post in the same week, your potential reach for twitter will be 50. Your Facebook friends and LinkedIn connections influence your potential reach the same way.