The normal procedure for takeoff in the RJ is to manually advance the throttles to close to takeoff power and then press the TOGA buttons on the rear face of throttles 2 and 3. Although these buttons are conveniently located near where the pilot's hands will be in the real aircraft, they are not very convenient for home simulators.
In the RJ Professional, the TOGA buttons can be triggered either by clicking the TOGA buttons on the back of throttles, triggering the AUTO THROTTLE TO GA control assignment, or by clicking a hidden clickspot on the lower left screw on the captain’s VHF NAV radio panel (pictured below).