How do I use grenades in the demo?

[Wheem 10]

I feel like an idiot, but I honestly cannot figure out how to switch to my hand grenades when playing the demo.

I've rebound a number of the keys, but don't see anything mentioning hand grenades in the options. I've tried the "switch weapons" key, but it doesn't work when I'm not carrying a second firearm or AT/SAM launcher. I'm playing Death Valley and I can see 4 grenades in my inventory, I just can't figure out how to equip/throw them.

[DieterWeber 0]

Press F to switch firing mods, and grenades.