I am assuming the resistor will be large, not small but then I don't know what your circuit looks like or the value of your current source or the operating voltage across your capacitor.
Bear in mind with any noise simulation it is the equivalent impedance that matters. Often adding a large value resistor in a circuit somewhere is not actually detrimental to the circuit noise because its impedance is in parallel with something else which reduces the noise resistance. For example, in your case you have a capacitor which will have a significant effect on the noise.
Maybe if you post your circuit it might help the discussion.
There are transient noise analyses which can be done which may help.
Keith.