TurboTax says I need to pay self-employment tax on referral fees received in 2022. Is this correct? If yes, is this tax payment included in my income tax bottom line?

Yes.

Referral fees received are self-employed income and are subject to self-employment tax.

Self-employment tax is reported on line 23 of form 1040 and is included in total tax on line 24.

Thanks for the help, MinhT1! I'm glad to know I don't need to write an additional check for the SE tax.