I was taught the pencil method but using a differnt implement.
I would call it the "THUMB" method. you use your thumb.
If it is a left hand hold, use your left hand thumb. For a right hand hold, use your right hand thumb.
With a left hand hold, put our left hand thumb next tot the left hand side of the DI and down by 70degrees. If you outbound track lies in that sector then you do a teardrop entry. You have to visualise the pencil line, but 110 degrees to the right gives you the parallel entry and the bulk of the DI delow your thumb is a direct entry.
Do the same for a right hand hold, except use your right thumb on the right hand side of the DI.
What I really like about the thumb method is:
Left hand hold - LEFT thumb
Right hand hold - RIGHT thumb
Sector with your Thumb (starts with T) is a Teardrop (starts with T).
With a pencil, you have to remeber which sector is teardrop or parallel and which way to slant the pencil.
Trevor Thom covers it in The Pilots Manual 3, Instrument Flying published by ASA is USA, but not in his book 5 for the UK.
Hope it helps.