Can I allocate foreign dividends between both RICs and other sources in TT for purposes of the foreign tax credit? How do I do this as TT only allows one allocation?

I totally agree with you and your frustration!  TurboTax is not very helpful in regards to Form 1116 and I haven't been able to find any online examples of a completed Form 1116 at any public accounting firm or website for the situation of a USA resident citizen taxpayer who has taxable income in the form of dividends [passive income] from a foreign country source whether mutual funds or ETFs or corporate stock shares which dividends are qualified per USA tax law and for which a credit is available to the taxpayer IF the taxpayer submits a properly completed Form 1116.

As a precautionary measure and based on my own experience, and a delay in receiving the credit due me, I now always file my federal return in printed paper form, and include with my return a copy of each page from my brokerage account that provides the details of the dates on which dividends were paid and the foreign taxes paid.  That enables the IRS to enter any additional data they deem necessary and to make any corrections they deem necessary.  By inclusion of a cover letter with my federal return, I authorize the IRS to make any corrections they deem necessary to that Form 1116.  Otherwise, I've found my credit and thus my entire refund due me to be held up by the IRS, typically for several months.