There is a secret reserve.
May a suggest to publish the sha256 sum of your secret reserve? In this way can everybody check after the auction is over that the reserved has not changed, thus making the auction more transparent. Remember to add a salt or keep the text format a secret:
example 1 (secret format):
2017.01.31 Killyouall acution...... the secret reserve is 100 BTC
hash: ac5a16ebca0e12650e65e68a657d158ad06913f06d924326c4b419c3785e5ac7
example 2 (adding a salt):
100 BTC e5672fa7291cd001
hash: 4d9e5c7fd42853c197a3dc654fa7ccfdec698d52dc3ffa7f3549312c0a196a51
All you have to do is calculate the sum of your string and publish it, at the end of the auction then all you have to do is to publish your string with the reserve price. If using the salt method then just include a reasonable long and random number to the string.