See Straddle handstand with 1 finger support and begin in this position.
Push through the base hand even harder.
The additional push should allow the support finger to briefly lift into the air. Allow the finger to float up an inch or two, then return it to the floor for stability.
Attempt to perform the finger taps from the one finger support position without moving anything in the lower body. Only push through the shoulder of the base hand to perform this drill.
Perform 5 controlled finger taps, returning to the one arm support position each time. If you can do this, you are ready to hold a Straddle one-arm handstand !