Hi i'm looking for a method to cast shadow onto my HDR or image background in Flamingo

Hi i’m looking for a method to cast shadow onto my HDR or image background in Flamingo. I see a Brazil post about using a special material… is there an equivelent in Flamingo or a way of making a surface receive shadow and only that to be visible in render… alpha chanel or such like - thanks in advance

It seems there used to be ‘shadows only’ on the ground plane panel… but it is not there now? Any other ideas?

OK it seems the answer is to make a plane under my object and click the flamingo tab under object properties and make it an alpha channel… bingo!