The four additions are LHP Miguel de los Santos, RHPs Wilmer Font and Fabio Castillo, and outfielder Engel Beltre. If you weren't a Latin American signee, then you weren't added.
Also per Sullivan, the Rangers have signed infielder Esteban German, outfielder Doug Deeds, and catcher Kevin Cash to minor league contracts. I suspect that each of those guys are just minor league depth guys.
UPDATE -- Also per Jason Cole, Wilmer Font just had Tommy John surgery, which means he's out for 2011.