The flag is -with-rtsopts, not --with-rtsopts, so you should add -with-rtsopts=-N to the ghc-options field. GHC Flag Reference.
Note that this will also require you to link with runtime support by adding -rtsopts to the ghc-options.
The flag is -with-rtsopts, not --with-rtsopts, so you should add -with-rtsopts=-N to the ghc-options field. GHC Flag Reference.
Note that this will also require you to link with runtime support by adding -rtsopts to the ghc-options.