Viewshed Analysis Workflow

For Path method, use the selection tool to identify a linear element.
Identify which end of the chosen element is the starting point. This is important as measuring along the line begins at the selected end and slightly different results may be achieved depending on which end is selected.
After setting the appropriate parameters and selecting the viewshed range, select Run.
Identify the view which should be used to calculate the viewshed.

The resulting analysis will be produced in the specified grid file. This file can be attached as any raster file for visualization.

If the path or element is moved or modified, make sure to select it again using the appropriate tool. When each is selected, a copy of the elements geometry is used for processing, not the original element.