How to "Call" a ball not caught

[Shmuelg]

I had this problem last night:

One out, R1 and R2. Rec ball, but the guys kind of take it seriously.

Batter hits a line drive to the shortstop. The ball hits the ground briefly (for a millisecond), and then goes into the SS's glove. No question in my mind, but it was a question in the mind of many of the fielders and runners.

I didn't call anything, didn't say the batter is out, didn't say "hey guys, run", or anything like that. Just kind of looked at the SS, and waited for things to happen.

They did. After a couple of moments, the SS figured out what was going on, and tagged R2, who had come off of the base, but was confused as to whether to run or not. SS then took two steps to second base, stepped on it, and I called R1 out. He had not run (he was confused, too).

I felt sorry for all of the confusion, and it would have been nice to make some sort of call that made everything clear right away, but I don't know what I should have done? Point to the ground? Call "fair ball" (OK, that was a joke, I'm not really asking that), or something else?