Oil leak rear of head gasket case

I have an oil leak from the rear of my head gasket casing. When running, oil kind of sputters out every now and again. If i put my finger down there i can feel a semi circle shape opening there. Should that be covered or sealed? What do i need to do to sort it out? I've tried to take a picture...

Thats your rocker cover and there is a half moon each end as well as the gasket

Not endorsing the quality of the parts, but for reference https://www.ebay.co.uk/c/1087480405

Ah, right so it's missing a half moon seal from the end. Thanks.