If you make a copy of the Probe Turn stat and add a check for a bet on the river to the expressions that will give you what you want.
A bet on the river is stored in the database field: holdem_hand_player_statistics.flg_r_bet.
See the
Tutorial: Cus tom Reports and Statistics for how to make a new version of a stat.
For instance, the cnt_t_probe column is defined as:
sum(if[holdem_hand_player_statistics.flg_t_bet and lookup_actions_f.action LIKE 'X' and lookup_actions_p.action NOT LIKE '%R' and holdem_hand_player_statistics.flg_p_face_raise and not(holdem_hand_player_detail.flg_t_has_position), 1, 0])
..so you can add the river bet expression, like this:
sum(if[holdem_hand_player_statistics.flg_t_bet and lookup_actions_f.action LIKE 'X' and lookup_actions_p.action NOT LIKE '%R' and holdem_hand_player_statistics.flg_p_face_raise and not(holdem_hand_player_detail.flg_t_has_position) AND
holdem_hand_player_statistics.flg_r_bet, 1, 0])
You would then probably want the "opportunities" expression to be when the player made the probe bet and had an opportunity to bet the river?
That would be:
sum(if[holdem_hand_player_statistics.flg_t_bet and lookup_actions_f.action LIKE 'X' and lookup_actions_p.action NOT LIKE '%R' and holdem_hand_player_statistics.flg_p_face_raise and not(holdem_hand_player_detail.flg_t_has_position) AND
holdem_hand_player_detail.flg_r_open_opp, 1, 0])