Normally RTD sensors are wired into a resistive Wheatstone bridge configuration, driven by either a constant current or constant voltage source, followed by a differential instrumentation op-amp with a amp gain set such the desired temperature measurement range falls within the voltage range of the A/D stage reading the output, in your case the Arduino 0-5vdc measurement range.
If you Goggle RTD you should get a lot of information on RTD interfacing circuits. One generally wishes to keep the current flowing into a RTD as low as possible to offset the 'self-heating' created by the current which can effect the measurement accuracy. RTD are among the best temperature sensors available, but do require careful interface design.
Lefty