You cannot add the Property Type/Usage field to a Tax Search because not all towns use it the same way (or at all).
But what you can do is sort your results by the Prop. Type column (which, by default, is on the far right side of the Single Line Tax display).
Then you can use the groups that relate to apartment buildings (4-8 Unit Apt, 9+ Unit Apt, Apt Bldg, etc).
Just be aware that, since not all towns use the same fields or naming conventions, your results are at the mercy of the towns you've used in your search.