The manual of advanced installing sysdig focus on RHEL6 only. To install sysdig on RHEL7, just need to modify this step:
2) Install the EPEL repository
......
rpm -i http://mirror.us.leaseweb.net/epel/6/i386/epel-release-6-8.noarch.rpm
We should install EPEL7 for RHEL7:
yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
Other steps are same! The you can play sysdig now!