Installing Origin VTA on P25

Forgive me if this topic has been covered in this forum before, but I could not find a thread discussing the installation of the Origin VTA adjuster.

I just received said item this afternoon. It will be installed on a Rega P25 with RB600 arm. I have removed the arm but am unsure of how the adjuster is to be fitted. Describing its shape as that of a top hat, it seems that I should flip the hat upside down and drop the top portion inside the armhole, leaving only the brim visible and resting atop the plinth. Is this correct?

It seems right to me, but alas the adjuster does not drop in the hole. I purchased this particular VTA devise because it's supposed to fit the existing Rega armhole. It does not. Before I pull out the grit paper for some *very light* sanding, I need to verify that I am approaching installation correctly.

O' wise sages of Audiogon, I beg for your input.
hope u get some responses here..i'm another one with a rega 25 who'd like to dial in vta better. there is a rega forum on vinyl engine that u could look at. and, a brit site, pink fish media might be a help if you're able to get into their archives.
Too eager to wait for an answer to my question, I put my dremel tool to work the P25. My inclination was correct. After lightly sanding the arm hole, the VTA adjuster slid right into place. My anxiety over permanently altering the plinth aside, installation was a breeze.

Thanks for your response, Amondrool. Don't stress over installing this adjuster. It's quite easy.