Generate a bid acceptance PSBT

You need a few things to generate a bid acceptance PSBT

inscription_id The inscription id to accept a bid of
seller_public_key The public key of current address location of the ordinal, usually 66 characters long, and is hexadecimal format

Now you need to POST /intent/accept with these included in the body.

You will receive psbtBast64 for signing.

Signing PSBTs using local wallet software

Sign all inputs of the PSBT using a wallet of your choice.

Submitting the signed PSBT to /bid/fill

Now that you have a signed PSBT, you will need to reuse the original parameters which generated the listing (required fields in section 1 of this guide).

In addition to those parameters you need:

price The price of the bid you want to sell your item for in Satoshis
seller_ord_address Your seller ordinal address for where the inscription is currently located
seller_receive_address Your seller payment receiving address
signed_accepted_bid_psbt The signed bid acceptance PSBT formatted as base64 or hex
unsigned_accept_bid_psbt This is the unsigned bid acceptance PSBT from above

POST /bid/fill with these parameters to sell your item for the bid!