OP_RETURN #howtostr
Use any TXT -> HEX (UTF8) and HEX->TXT web browser convertor
On ur bitcoin-qt node wallet console or bitcoin-cli
createrawtransaction "[]" "{\"data\":\"426974636F696E2069732046696174697A6564\"}"
fundrawtransaction
signrawtransaction
sendrawtransaction
(copy paste hex output in each above in the next subsequent command)
That’s it – To see
getrawtransaction
decoderawtransaction
or use explorer web / api / convert HEX to TXT
*** 80 Bytes ***