As requested , here is a capture of [my blog] post for an Automator Service that works for me in Mavericks.

Code for Applescript in step 2

on run {input, parameters}
    
    tell current application to activate
    
    
end run

Code for Applescript in step 5

on run {input, parameters}
    set theApp to (POSIX path of (item 1 of input))
    repeat with i from 2 to number of items in input
        set this_item to item i of input
        tell application theApp to open this_item
    end repeat
    tell application theApp to activate
end run

After Saving the Automator Service go to System Prefs. and add your shortcut to it.

As requested , here is a capture of [my blog] post for an Automator Service that works for me in Yosemite .

Code for Applescript in step 2

on run {input, parameters}
    
    tell current application to activate
    
    
end run

Code for Applescript in step 5

on run {input, parameters}
    set theApp to (POSIX path of (item 1 of input))
    repeat with i from 2 to number of items in input
        set this_item to item i of input
        tell application theApp to open this_item
    end repeat
    tell application theApp to activate
end run

After Saving the Automator Service go to System Prefs. and add your shortcut to it.