You could spell it out - "R-I-S-C".

The first three letters could be "Rice" or "Rise" instead of "Riss".

I suppose you could have a soft "C" - "risch" - but that's a stretch and reminds me of Sean Connery.

Never underestimate the power of people to put weird sounds to letters. I used to do a lot of network stuff and somebody once pronounced MPLS (which you very much need to spell out) as "mipples" and it scarred me for life.