Trying to understand parent fingerprint in HD wallets I'm trying to implement a barebones HD wallet generator in C#.  I'm starting with a mnemonic and derivation path m/0' and want to generate BIP141 p2wpkh-in-p2sh addresses.  Obviously for the Master Node the fingerprint is 0x00000000, but when I get to depth 1 (0'), I need to calculate the fingerprint of the parent key.  My question is, is the formula RipeMD160(parentPrivKey) or RipeMD160(SHA256(parentPrivKey))?  I've been looking at Ian Coleman's implementation in javascript (https://iancoleman.io/bip39/) and he seems to do the latter one.  However, on this site under "Parent Fingerprint", it says it's the former.
It's ripemd160(sha256(parentpriv)) also known as hash160(parentpriv) source. There is also a python implementation here