Total measure settings can be found in the Configurations window of Smart Dimensions:

There are settings for Horizontal, Vertical, and Diagonal total dimensions.

You can switch any of them ON or OFF.

Horizontal and Vertical Total Dimension setting will give the overall dimension of all elements that have been selected to be Included in Total Measure.

Example. Only Walls have been selected to be included in the total measure:

Now, if Face-based details are also selected to be Included in Total Measure, then the vertical dimension will include them as well:

You can select a few other options as well.

Dimension Side - just select where the dimension line should be placed.

Dimension Type - select from the dimension styles available in the project.

First Dimension Offset - this value will be multiplied by the Dimension Line Snap Distance parameter and used to offset the first dimension line from the measured element. 

Text Note - any text may be added here and it will be created near the total dimension line.

Also, there is an option for Diagonal Dimension. This will place the diagonal dimension for the assembly from bottom left to the top right corner using the selected dimensioning style:

Measure Elements from Linked Models - will allow your dimensions to snap elements from linked models. In the example below an MEP project has a linked Revit project with walls and openings (face-based void families). Smart Dimensions can measure those now: