Do you add an s or es to a last name ending in ch?

To form the plural of a name (or any other noun) that ends in 'ch' you add '-es'.

Hatch, Hatches. Winch, Winches. Rich, Riches. Such, Suches.

There is an exception in the case of Words where the 'ch' sound is not pronounced in the normal English way. For example, the plural of the German composer Bach is Bachs, not Baches. That is because the Words 'Bachs' is easily pronounceable, whereas the Word 'Hatchs' is not.