TLC555-Q1: Frequency divider circuit diagram

Hello,

I believe the figure reference here is a mistake. If you look at the TLC555 datasheet section 7.3.3, the circuit it refers to is the Monostable circuit. There would be no modifications to this circuit. If you added an Rb like in your image, the timing capacitor would take longer to discharge. As you see in figure 10, the capacitor discharge is sharp which confirms to me that this section should be referring to the Monostable circuit in figure 3. Also, figure 10 gives the component values in the top left corner, there is no Rb listed. 

The input voltage mentioned in figure 10 is applied to the Trig pin. The input signal has a frequency 3 times greater than the timer, so the timer is only triggered every 3rd pulse from the input signal.