Tested with geth instance=Geth/v1.8.10-stable/darwin-amd64/go1.10.2
geth --rinkeby --rpc --rpcapi="personal,eth" console
Ruby version: 2.5.0 Rails version: 5.2
with postgresql psql (PostgreSQL) 10.4
bundle install
rails db:create
rails db:migrate
rails s
and sign up for creating new user