Deductions & credits

Here is how to report this. 

1.  Go to Federal
2. Deductions and credits 
3. Estimate and other taxes paid 
4. Foreign Tax Credit>start or revisit
5.  As you go through the screens, when it asks "Tell Us About Your Foreign Taxes" select none of these apply.
6. When it asks if you wish to take the deduction and credit, take the credit.
7. Continue through until you reach a screen that says "No other income or expenses" Say no
8. Continue through until it asks the income type, say Passive Income
9. Next add a country pick UK.
10. Other Gross Income say UK Pension income  and the Gross Amount of the income
11. Continue through the interview until it asks for the foreign taxes you paid, here record the amount of foreign taxes you paid..  
12. Now you are done reporting the foreign taxes. Just keep going through the section without making any more entries. You will have finished reporting your gross income from pension and the foreign taxes paid.