The CDE or CEE renunciation amount is usually reported on a T101 slip. If that is the case, and to the extent that there are resource profits, you should enter the deductible amount on the Other Deductions worksheet in the free-form area for line 40.
This will transfer the amount into the section of the T3 that calculates the net income. The slip substantiating the deduction should be attached to the return when it is filed.