How to assign CTRL+F1 to sp_whoisactive in ssms 2012?
Click on Tools > Options.  Then navigate to Environment > Keyboard > Query Shortcuts. In the stored procedure column next to Ctrl+F1, type Sp_whoisactive.

Next navigate to Tools > Options > Environment > Keyboard > Keyboard, and find the command Query.CustomSP1. Assign the shortcut Ctrl+F1. Then search for the command Help.ViewHelp and remove the mapping for Ctrl+F1 there.