HOW PAY RCM AND TAKE ITC

You can visit this link for detailed information https://www.cbec.gov.in/resources//htdocs-cbec/gst/reverse-charge-mechanism-08aug2017.pdf

I DID NOT UNDERSTAND BY THIS LINK .

IF I PURCHASE GOODS OF RS .10000/- FROM AN UNREGISTERED DEAR AND I DEPOSIT OR CALCULATE 1800/- OF CGST AND SGST ON THIS URD PURCHASE .
HOW I WILL TAKE ITC OF RS.1800/-AND REDUCE IT IN PAYABLE GST .

FOR AN EXAMPLE :


CGST PAYABLE ON URD PURCHASE -900
SGST PAYABLE ON URD PURCHASE-900
LESS- RCM ON URD PURCHASE CGST-900
LESS- RCM ON URD PURCHASE SGST-900
BALANCE PAYABLE -00

IS THIS IS CORRECT WAY OR NOT ?
PLEASE EXPLAIN .