I bought a Sig XCompact (not rxp compact) and installed a sig romeo1Pro. As you know, you can't install a rear sight in this configuration but the romeo1pro does have a notch for co witnessing the front sight but the standard front sight is too low causing the gun to shoot very high when co witnessing this rear notch.
Has anyone installed a taller front sight to co-witness this configuration? Someone online said to use a .300 front sight but I can't find any factory sig sights that tall. Any feedback would be appreciated.

Get a suppressor height sight. I'd suggest Dawson.

You could send it back for the upgrade but shipping is in you so I'd do it local. Swapping the front sight is not difficult with the correct tools. A quality sight pusher is a must or you risk snapping the sight base.

Sig markets the Xray in suppressor heights but usually as a set. Paying for a rear sight you can't use.

Down side with Dawson is they require fitting.

thanks that's what I was thinking.

The only sold as a set thing by Sig is really annoying. I'd like an X-Ray3 front on an M17, but don't need the rear since it has the blacked out sight plate already. And for an optic, the X-Ray3 suppressor front would be fine. And it's not like you can buy a set and sell just the rear to someone.

It was also kind of annoying that the RXP has front/rear suppressor sights and the optic, but the non-optics have the integrated rear sight plate. Why not have the RXP slide standardized (except M17/M18 since they are following the military pattern) and have a filler plate like everyone else?

I don't want to buy an RXP because I'm not going to use a Romeo 1 Pro. Either DPP or an adapter plate for an RMR, or possibly an Aimpoint Acro when they get the P320 sight plate problems worked out.