Can anti-radiation missiles be used to target stealth fighter aircraft?
There are many anti-radiation missiles in many arsenals, they are designed for air to ground missions, attacking surface to air missile radars from a long distance. I don't know whether it would be possible for an anti-radiation missile to hit an air target.
If we assume it is possible your idea has a significant flaw in that stealth aircraft turn off their radars when they are on a stealth mission. Running a radar is like holding a flare in the middle of a field on a dark night, which is why they don't do it, at least not using conventional radars.
Some stealth airplanes don't even have a radar, for instance the F117. Typically attacks were done using GPS for precision navigation to the target, which is then attacked using precision munitions like laser guided bombs or GPS guided bombs or missiles.
Nowadays here are advanced radar systems that spread signals over multiple frequencies which will blend in with other signals, and can be directed in specific directions to avoid being detected. If a radar beam isn't pointing towards a sensor then the radar won't be detected.