I am trying to fill in the Out of State Credit Worksheet and I don't know what to fill in as the amount

When you moved from one state to another during the tax year, complete the nonresident/former resident state first. Then, refer to the former resident state return to complete the other state tax credit questions on your new resident state return.

Arkansas allows a credit for taxes paid to another state if the amount of income you are required to report to Arkansas as Arkansas income is also being taxed by the other state. See this Arkansas webpage for more information.

For the Arkansas credit calculation, TurboTax will need you to enter the amount of income that was taxed in both states. If you received any California-source income after you moved to Arkansas, that would be the double-taxed amount. 

As a part-year resident of California, you pay taxes on:

• All worldwide income received while a California resident
• Income from California sources while you were a nonresident

See this California FTB webpage for more information.

See also this TurboTax article on multiple-state situations.