Adding wkhtmltopdf docker image into RHEL based Docker image

I have a java project that essentially builds out a pdf from any html file input into the system. I am using wkhtmltopdf (https://github.com/openlabs/docker-wkhtmltopdf) to build the pdf image of any css3 code we pass it. Works great locally, but when we tried:
FROM oracle-jre-hardened:latest
ARG RHEL_ACCOUNT_USERNAME
ARG RHEL_ACCOUNT_SUBSCRIPTION_FILE
ARG RHEL_RUN_UPDATE=true

we cannot figure out how to install wkhtmltopdf as an rpm on rhel?

Thanks in advance for any advice.