My apologies Brodie After looking up the rules you are correct . The % is known at the time of scratching and can be worked out by the following rule. Yes maybe the % should be put up beside the scratched horse however it gets a bit more complicated when their are other late scratchings Perhaps this is why .
FINAL FIELD DEDUCTION FORMULA The nearest whole number percentage, using Swiss Rounding, obtained by dividing 80 by the product of the number of RBPs multiplied by the Odds for the Race Entrant at the time it was Scratched from a Race, provided the Odds are less than or equal to Maximum Deduction Odds = 80/(RBPs x Odds) (Rounded to nearest whole number). Maximum Deduction Odds shall be $35.00 Example: Where a Race Entrant paying $5.00 to Win and $1.33 for a place (3 RBPs)is Scratched, the Return on successful Final Field Win Bets placed prior to that Scratching will be subject to a deduction of 16% (80/(1x5)). Successful Final Field Place Bets will be subject to a deduction of 20% (80/(3x1.33)).
In the event that there are two or more Scratchings, Final Field Deductions on bets placed before those Scratchings shall be calculated by applying all Final Field Deductions. Bets placed after any Scratching shall be calculated by applying the Final Field Deduction for subsequent Scratchings only.
We all learn so hope this helps next time so the shock is not so great