illegal slide
 

Fed:
No outs R1 on first. Ground ball to F5, she bobbles it a couple times but recovers and throws to F4 for force out on R1 at second. F4 has no play at first & doesn't attempt a throw to F3. But, R1 makes an illegal slide into F4.
What, if any, penalty can be called on R1 for her illegal slide into F4?
Thanks

Rule 8-6 covers this. If a runner is being played on, and makes an illegal slide, she is out and the ball is dead. Fed considers this an act of interference. If F4 has no play on the BR and did not attempt one, we cannot rule retired runner interference on the illegal slide, as that requires an act which hinders the defense from making a play. If the slide/contact was malicious, as in slashing or kicking with the spikes, then we could have MC and its associated paperwork. Last but not least, if the slide was not malicious but simply appeared to be unsporting, I don't have a problem with issuing a warning.

If it was none of the above, and just bad softball, there's nothing else to do. She's already out; we can't get her out again.