Installation:
Download and unpack the initial_config.cfg to your \...\The Riftbreaker\conf folder.
Overwrite the old file if prompted.
(This may overwrite your old graphic configuration, so double check afterward!) 

Turning off TXAA manually:
1. Go to the \...\The Riftbreaker\conf folder.
2. Open initial_config.cfg with a text editor of your choice.
3. Find 'set r_anti_aliasing "txaa" ' in line 5.
4. Change it to  'set r_anti_aliasing "smaa" '.