Load balancing to distribute workload across multiple nodes in a cluster works with RAP out of the box since version 1.0.
One thing to mind though when setting up a load balancer for RAP applications is that it must be configured to use stcky sessoins (session affinity). This entails that once a session is started, the same server serves all requests for that session.
For information on how to set up load balancing, refer to the servlet container documentation. E.g. Tomcat