Open the Smart Dimension menu on the 3D Document Toolbar. (Click the drop-down arrow to the right of the Smart Dimension icon.) Select Smart Edge Dimension. Mouse over and select a highlighted edge. Optional: Select Lock tool to use the command more than once. Enter a hyperlink to a file or to a document and user view within the current file. Position your cursor on an edge. (Selectable edges are highlighted when you mouse over them.) Double-click the left mouse button to measure the edge length (default). Click the right mouse button to bring up a context menu containing additional measurement options, then make your selection.
If the edge you select is an arc, the context menu will contain more measurement choices. Drag and click to position the label in the scene. Note If you want to add several of the same type of markup, you may select the Lock tool checkbox that appears when you select a markup command. This will allow you to keep adding the same type of markup to the scene until you click Stop.