[morzh]

The rule of a thumb often is to make the ripple rating equal twice the load current. That only goes for the very first cap (paralleling the rectifier tube). He rest do not see as much ripple.
So if the rectifier supplies the radio with 50mA of current, the 100mA rating is enough.
I use higher rating so I do not have to think about it. I buy Panasonic caps that are about 600mA rated and this is good for just about any rectifier, even in the Eico stereo amp.