Opening .tblk file with root privileges
Right click on the file, go under informations, scroll down to permissions and click on the lock. Then enter your administrator password to unlock it. Then, it you're not allowed to read, write and execute click on the +, select your username on the list and press select. Then change the combobox to read, write execute. 
Then, you should be able to open your file by right clicking and clicking on open with -> Tunnelblick.