Found on the right hand button menu during Insert Dimension. This feature allows you to snap the start and end positions of the dimension directly to the edges of the picked items between which you wish the dimension to span.
Snap To Item will cause the dimension start or end point to be at the closest edge of the item selected. If a pad is being dimensioned then the snap point will be at the pad’s centre.
Shortcuts
Default Keys: None
Default Menu: None
Command: Snap To Item
Locating this option
Available from: context menu > Snap To Item option