PWM controlled variable resistance
As shown, the job of the capacitor is to destroy the MOSFET. 
ie it is incorrectly shown.
When the MOSFET turns on it will dissipate the capacitor energy in the MOSFET.
This circuit would be better with inductive smoothing, when it would become a buck converter, but ...

Smoothing current waveform:  

Instantaneous voltage changes across the capacitor must be avoided as in theory they are impossible and in practice attempts to cause then produce high currents and undesired energy dissipation. So,

Add second 1R or split 1R into 2 x 0.5R.
Connect capacitor across either or the two split-resistor portions. 

Just smoothing ammeter reading: 

Connect the capacitor 'across' the ammeter, from ammeter +ve to ammeter -ve.
The usually low impedance of the ammeter makes this hard to do well - ie a largish cap value is required for a given PWM frequency.

This will have a small smoothing effect overall but if Rmeter &lt; 1/2 Ohm adding the capacitor across the split  1 Ohm is more effective.