When reading the King James Version of the Bible, we often hear, e.g., "maketh" pronounced in two syllables. Is this an accurate reflection of the pronunciation of that word when it was commonly used?
Words existed such as putteth, standeth, and goeth. To my mind, then, it seems reasonable to assume that the entire suffix was its own syllable, not included with the one that came before it, but pronounced distinctly, as "put-eth" or "stand-eth", for example.
One other note: the correct suffix is -eth, not -th as you have it in the title.