The datasheet for the ADP1071 describes setting switching frequency by using a single resistor RT connected to AGND1 and then gives a formula for a resistor divider which has nothing to do with RT (has in it RA and RB that were not mentioned before). Looks like there is something missing in the description or the formula.
Apologies for the confusion. Please treat R_TOP+R_BOT= R and place R on the RT pin to AGND1. See fig 27 for more details below.
I will make a change to the datasheet and it should be available soon.
Lt Comm Data.