By default, the linter plugin looks for a config file called .rubocop.yml in the current directory and its parents. To override the config file path, you would add this to the linter settings:

rubocop.yml

---
Rails:
  Enabled: true

Style/AsciiComments:
  Enabled: false

Metrics/LineLength:
  Max: 120

Metrics/ClassLength:
  Max: 120

Documentation:
  Enabled: false

sublime settings

"rubocop": {
    "args": ["--config", "path/to/rubocop.yml"]
}