Preliminary RTD calculations are shown below, given an input of 10 V and desiring a few mA of current. It looks like R_ref should be at least 1 kOhm (refer to plots/circuit below), keeping in mind we need to have <10 V input for the ADC.

RP: The Red Pitaya Software was updated to OS 2.00. All examples on the RP website should run without issue.