Finding /blog/post.php when all of perch is in a subfolder

I've not installed Perch in a sub-folder but what do you have for "Blog post page path" in Admin - Settings?

I do have the folder it's in there, so it's /[FOLDER]/blog/{postSlug} and in the url for the link to an individual post it's correct when I look at it rendered in the page, which is why I'm stumped on it not finding the /blog/post.php file.

So the url that I'm getting is /microblog/blog/2018-09-06-post-37 for the latest post when I have <perch:blog id="postURL" /> in the href. I'm doing the URL rewriting for a clean url that's talked about here: https://docs.grabaperch.com/addons/blog/examples/clean-urls-perch/. My rewrite is as follows:

<IfModule mod_rewrite.c>  
    RewriteEngine on  
    RewriteRule ^microblog/blog/([a-zA-Z0-9-/]+)$ /blog/post.php?s=$1 [L]
</IfModule>

Perch is sitting in a folder of microblog on my site (at https://susanjeanrobertson.com/microblog/), I'm using it just for that and then the rest of my site uses Jekyll. I realize this is a bit of odd usage, but I didn't want to change over my whole site when I really only wanted the ability to update my microblog from the web easily.

It is the correct url, but when I go to the url I get the 404 that it can't find /blog/post.php which is why I'm confused.......

the file is there at /microblog/blog/post.php should I think it should find it, but it's not :(

So I did an experiment to see what happens and if I move the file for the post.php to a folder blog at the root, it works (with errors due to not finding runtime.php etc because I just wanted to see what happens and wasn't trying to make everything work.

Is there a reason that Perch is looking for that file at the root when I have the entirety of Perch in a folder? In my blog admin settings I have my url as being the one with the /microblog on the end and I've set everything else up for that, but Perch is looking for that file in a place that I don't think it should be looking. And I'm not sure why.

Routing I think. For some reason Perch is looking for the post.php file in the wrong place and I have no idea why.

Yes I do, on my production site I'm not linking to the individual posts yet, so I've left all the other stuff there for when I figure out what the problem is.

So I changed the rule to this:

<IfModule mod_rewrite.c>  
    RewriteEngine on  
    RewriteRule ^microblog/blog/([a-zA-Z0-9-/]+)$ /microblog/blog/post.php?s=$1 [L]
</IfModule>

and it seems I'm getting closer, I now have my site 404 page instead of the browser just telling me it can't find /blog/post.php

The url for the posts is correct now and the rewrite (I think) is correct, but it just doesn't want to use the individual post page to do this.

And I'll be honest, maybe it's time to give up here, because I'm clearly now figuring out what the problem is or how to solve it and I don't know if I can.