Is that the one from NS kimura, where you step over uke and then sit back so you're on your back and you have the kimura with your calves against other guy's back? That's my preferred kimura finish but I'm not very flexible and often struggle to get into that position without getting bumped over while I'm trying to step over. Tarikoplata looks like it's pretty much that, but with the lapel holding the kimura tightly in place and might be more practical for me.
There's a few guys at my gym who are good at NS choke, and it's probably 30% for me so I go for it if possible. But it's a slow burn sub and you can't rush it or you won't settle in properly. I finished one yesterday during rolls but that's only possible if my ribcage is deep enough to force other guy's head to turn away. If it's a bigger, stronger guy and he's resisting that, I just go to kimura or back to side control. But as an old guy grappler, NS is probably my favorite position for control and transitions.
Let me describe a few details that I think could help.
First, I would ask if you're joining your hands or not for the finish. I prefer NOT joining my hands, but just having one wrist on top of the other.
Let's assume you're choking with your left arm. Try this just sitting in a chair.
Don't lift, don't squeeze. Put your palm on your sternum, slide your hand across your chest toward your right shoulder. This will drive your left bicep into their left carotid. Don't think about the crook of your elbow, that will just make it cranky, we want a clean blood choke. Now, instead a rib cage, think lat. You want your lat, with the bottom corner of your shoulder blade, in their right carotid. As you drive your left arm across your sternum, you walk in a clockwise circle, pressuring the right side of their neck with the very upper portion of your lat, as high up on your own armpit as you can wedge them. Now, and only now, do you think about your hands. Palms up. Back of your right hand on the floor, back of your left hand just above it, and NOW turn your wrists to you. But if you've done the other things correctly, you'll never even need to do that.
Once everything is set up, it should be practically effortless, and a VERY quick tap.