Rails Peddler gem: Using Amazon MWS Feeds API for adding products to Amazon seller central store

I am trying to add a product to the amazon seller account using amazon mws feeds api. I am using Ruby on Rails and peddler gem. But i couldn't find any documentation/example of how to add a new product. There's a function given to submit feed (link). But i am not sure about how to send 'feed_content' parameter. Is there any example of how to do it? I am able to make the connection:

  client = MWS::Feeds::Client.new(
  marketplace_id:        'marketplace_id',
  merchant_id:           'merchant_id',
  auth_token:            'auth_token',
  aws_access_key_id:     'aws_access_key_id',
  aws_secret_access_key: 'aws_secret_access_key'
)

Kindly share any example or any suggestions of how to add a product. Thanks in advance.