It’s an amalgamation of them. The original editor largely used the Textus Receptus, but in certain cases where he didn’t like it (such as passages with a high Christology) he selected other readings. The 2009 edition also claims to use the Shem Tov Hebrew Matthew, though there is nowhere any clarification on which Shem Tov MS. was used as the basis for it.

VERY GOOD QUESTION JOHN. https://www.youtube.com/watch?v=k59D_35LKgs https://www.youtube.com/watch?v=7wPpoobocWw