Everything is in the I-864 instructions. You need to really study them. I second advice on seeking legal help as this is now your second attempt at filing.
“For example, you may include a recent letter from your employer, showing your employer's address and telephone number, and indicating your annual salary. You may also provide pay stubs showing your income for the previous six months. If your claimed income includes alimony, child support, dividend or interest income, or income from any other source, you may also include evidence of that income.”
https://www.uscis.gov/sites/default/files/document/forms/i-864instr.pdf
We sent an employment letter from HR and 6 months of most recent paystubs. No RFEs, approved over 2 years ago. At the time my husband was also hourly and paid weekly but HR had no problem calculating that into an annual salary. There are also calculators online that help do that.