Hello @jhackney1972 , @davebYYPCU , @laughingcreek and the Fusion 360 forum,
Laughing's comment 'project works by projecting something from outside a sketch (another sketch object, a face, an edge, a body)
INTO the sketch you are CURRENTLY editing.' makes a lot of sense.
For instance, a clear implication is that one must be editing a sketch to project the geometry of another object
into the sketch which is being edited.
I believe what is neeed is for the geometry of the Base Plate to be projected into the Countersink Holes Sketch.
So the Countersink Holes Sketch. was place in edit mode.
And the Countersink Holes Sketch is right clicked and thes are the options available. Can'tBase Plate Body
seem to find 'Project/Include' ot 'Project'
.
So with Countersink Holes Sketch being edited a right click was done on the Bae Plate sketch. Options:
And so also the the Base Plate Body was right clicked. Options:
So apparently the model is some mode that prevents the 'Project/Include' ot 'Project' option available.
Have read several sections on Project and watch four videos on the subject. I think I need to know
what is the method or mode that is required for the model to be in for the Project option to
to appear. Didn't seem to get that info from these investigations.
Looking back at the screen shot in laughingcreek's post it is noticed that the Project option is
being accessed from the Create tab
So have updated process as follows:
Base Plate w Countersink Holes
1. Create Component. Name Base Plate w Countersink Holes 230124
2. Create Sketch Name Base Plate
3. Select Center Rectangle tool. Make rectangle 74 x 74 mm
4. Create center PIR hole. Choose Circle Tool. Dia.: 24 mm
( I tried putting the countersink hole circle in the
Base Plate sketch but when the Base Plate sketch was extruded
it extruded the countersink hole circle as cylindrical
hole in the Base Plate. So I think the best practice would
be to extrude the Base Plate sketch and then create a
sketch for the countersink holes and revolve the countersink
holes as partial cones in the Base Plate.
4. Finish sketch.
5. Extrude sketch Extrude: One Side, Distance:3.2 mm, New Body, OK
6. Filet two outer corners 6 mm
7. Create Sketch. Name Countersink Holes. Select top face
of Base Plate for plane of Sketch.
8. Select Circle Tool. Make circle 6 mm.
9. Finish Sketch
10. Edit Countersink Holes
11. Create > Project/Include > Include
12. Selection Filter: Specified Entities
13. Select all the lines and circles in the Base Plate Sketch
and click OK
14. Constrain the countersink circle to be horizontal
with Base Plate centerpoint.
From here tried using Create > Hole but that tool
does not seem capable of creating a simple partial
cone. So I think I need to do Revolve Cut.
But when I draw the triangle to be revolved
to do the cut it is being drawn in the plane
of the Base plate and and the cone is needed
perpendicular to the Base Plate so I think
I need to creat a plane perpendicular to the
Base Plate and then create a Cone Revolve Sketch in that plane
and plane a project geometry of the Base Plate Body
into the Cone Revolve Sketch

15. Construct > Offest Plane One of the planes
offered is thru the Base Plate center point so
the Z/X plane is selected.
16 Create > Sketch Name Cone Revolve Sketch
17. Create > Project/Include > Project
Selection Filter Selected Entities. Select
Sides and midpoints and countersink hole
centers. Click ok
18. Using Line Tool draft triangle describing
cone to be cut. Finish Sketch
19. Select triangle and select Revolve and the
Axis and click OK
The countersink hole is drawn correctly. (Yea.)

Now struggling with mirroring the countersink hole
to the other side of the Base Plate. Have reviewed
Hackney's excellent video but there is something
that needs to be chosen that is not being picked up.
Thanks.
Allen