The Rays currently have veteran Jose Molina pegged as their starting catcher, but Scott Miller of CBS tweets that several in "the industry" do not expect Molina to play more than 80 games this season. With career minor leaguers Jose Lobaton and Stephen Vogt slated in the backup role (a combined 54 MLB games between them; all Lobaton), Miller states that several industry insiders expect the Rays to pick up another, more experienced catcher.
The Royals seem to be in the most dire need for catching depth as their starting catcher, Salvador Perez, will miss 12-14 weeks following knee surgery undergone this morning. Brayan Pena is now the only available catcher on the Royals roster with backup catcher Manny Pina also on the rebound from knee surgery.
Unless someone were to willingly pull Jason Kendall out of retirement--not likely, though possible for the Royals as he's at camp as a coach--only two veteran catchers remain on the free agent market: Ivan Rodriguez and Ramon Castro.
The Rays made it known earlier this week that they are not interested in Ivan Rodriguez, so it seems that Castro would be their only other option via free agency.
Both Rodriguez and Castro would seem to be on the table to address the Royals' issues at the backstop position.