Take a look at the US- China treaty, articles 17 and 18 to see what income needs to be reported. Taxable retirement income is reported on a 1099-R. Since you don't have a 1099-R, you would use the Substitute 1099-R which is Form 4852. The program will generate it for you.
Depending on the state treatment of the pension, there may be a work around to report the pension as other income. You may have to mail the return.