Do you want to count exactly the times a player raises and then calls a 3-bet preflop and is in position on the flop?
cnt_p_rfi_call3bet_ip =
sum( if[ holdem_hand_player_statistics.flg_p_first_raise AND holdem_hand_player_statistics.enum_p_3bet_action='C' AND holdem_hand_player_statistics.position < holdem_hand_player_detail.val_p_raise_aggressor_pos, 1, 0 ] )
cnt_p_rfi_face3bet_ip =
sum( if [ holdem_hand_player_statistics.flg_p_first_raise AND holdem_hand_player_statistics.flg_p_3bet_def_opp AND holdem_hand_player_statistics.position < holdem_hand_player_detail.val_p_raise_aggressor_pos, 1, 0 ] )
Then build a stat with Value Expression:
(cnt_p_rfi_call3bet_ip / cnt_p_rfi_face3bet_ip) * 100
See the
Tutorial - Custom Reports and Statistics for a walkthrough of building a stat from these expressions.
NOTE: there are a few cases where the position < raise-aggressor-position check won't work correctly, but these are cases where someone else called the raise and then 4-bets.