When creating a perimeter if there are physical obstacles blocking your view, you have two options. 

For most obstacles you can use the placement guidelines which appear when you slow down your camera near a point. Using these guides you can locate the corner based on the seems between the walls and floor.
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Occasionally, an obstacle will take up the full length of the wall without enough wall visibility to use the corner guides accurately. In this situation, it is easiest to create corners in front of the object so they are lined up, then fine tuning the boundary against the cabinet to push it back.

Remember you can always undo if the point isn't placed properly or you can complete your perimeter and come back through to adjust point positions.