Schefter points out that the Titans seem like a logical fit based on the fact that they have former Falcons offensive coordinator Mike Mularkey on their coaching staff.
This is the first reported visit since the Falcons cut him loose in a move that freed up $3.5 million available cap space.
Douglas, 30, was in the final year of his four-year, $12.5 million contract when he was released.
In 2014, Douglas appeared in all 12 games and caught 51 passes for 556 yards receiving and two touchdowns. Pro Football Focus rated Hartline as the No. 64 receiver out of 110 qualifying players.