Sounds a lot like the recipie my great aunt taught me as a teenager, but I can only assume that Rienzi white clam sauce is a premade suace.  The difference was that instead of the white clam sauce, she told me to use dry white wine and butter and a bottle of clam juice.   BTW, did buy all ingredients (clam juice and canned clams) a while ago, but the little ones absolutely refuse to even try it and am really not up to making 2 dinners on the same night since I am now feeding at least 7 (sometimes up to 12 if my 2 children's friends come for dinner, even though my 21 year old lives on her own - you know - "Mom's mooch a meal"  LOL).