Use the --timeout flag to change the timeout.
herbie shell --seed 2019072 +o rules:numerics
(FPCore (F B x)
:name "VandenBroeck and Keller, Equation (23)"
(+ (- (* x (/ 1 (tan B)))) (* (/ F (sin B)) (pow (+ (+ (* F F) 2) (* 2 x)) (- (/ 1 2))))))