You can load isolated foundation families by clicking Modify | Place Isolated Foundation tabModel panelLoad Family.
Rectangular isolated foundation
The Bottom Elevation of structural foundations (footings) is reported in a read-only instance parameter called Elevation at Bottom. You can then display this value in a view by tagging the foundation with the Structural Foundation Tag with Elevation tag. It is available from the family library, under Structural/Annotations. For more information, see Applying a Tag by Category.