The page does say it requires a header but that's wrong. I submitted an update to the page.
It does state what the checksums of the original ROM file are:
Database match: Mega Man X (USA)
Database: No-Intro: Super Nintendo Entertainment System (v. 20180813-062835)
File/ROM SHA-1: 449A00631208FBCC8D58209E66D0D488674B7FB1
File/ROM CRC32: 1033EBA4
So use Hasher-js
and check your ROM. You'll probably have to remove the header. If you have the right ROM without a header, you should see exactly what is quoted above. If the File and ROM checksums are different, then it has a header.
You should see these details as well:
Platform Super Nintendo Entertainment System
Format SNES ROM image
External Header No
File size 1572864 ($180000)
Rom size 1572864 ($180000)
Calculated checksum 55FB
Checksum valid Yes
You can also check the patched ROMs and they should say "Checksum valid Yes" (I just love a good checksum). Don't bother adding a header after patching the ROM.