1. Select File or folder you want to RAR.
Right Click > "Add to archive".
2. In General tab Check the "Put Recovery Record".
Recovery records can allow WinRar to correct some errors depending upon the size of the recovery record added.
3. In Advanced tab set Recovery Record in percentage.
The greater the % percentage of recovery record, the more that can be corrected. But it does increase the file size so many people do not like having to download more data that they will never use.