In the Better Bridge articles written by David Lindop, husband of Audrey Grant, he says you need 13 pts
to make a Takeout Double in the direct seat.
He also states that since you are likely to become Dummy after
Advancer has named a suit, you should count Dummy pts, 5-3-1.
Thus with a 4=4=5=0 hand you may make a TO with only 13-5=8 pts.
Is this sound bidding? Counting short pts before you have established an 8-fit seems unrealistic.
Personally I prefer to base a TO on 10+ number of losers in the opened
suit. As an alternative I count only 3-2-1 or 2-1-0 for a short suit.
Suppose you have a 3=4=5=1 hand as Doubler, what point count
would you assign to this hand in addition to the HCP?
Plus... it's free!