Sending prc file to kindle

So I used to be able to download .prc files in safari and choose “open in” Kindle.

But this option is removed after the new update. Now I can only send file to Kindle. However it only accept .mobi files and I have to enter file and author names, takes up a lot of time.

I tried sending a few different .prc files but Kindle keep saying “wrong file format”.

What do I do?