The Sulphurites lost the game 3-0, but actually performed better in the second half with five unsigned players on the pitch than they did during the opening 45 when they only fielded one.
And, Simon Weaver was sufficiently impressed by what he saw that he has decided to offer one of those involved against the Millers a permanent contract.
The Town boss is still planning to add at least three more bodies to his squad before the 2022/23 League Two campaign gets underway on July 30 and he plans to give the majority of those involved against Rotherham further chances to earn themselves a deal at Wetherby Road.
"They did well overall," Weaver told the Harrogate Advertiser. "One of the players we have offered a contract to and we are waiting to hear back.
"Of the other lads, there's one who played in midfield who we won't be inviting back, but the others we will continue to look at in training this week. There's also an in-house game that we are holding behind closed doors, so they'll play in that and also be in contention for the Huddersfield fixture on Saturday.
"There were some good performances on Tuesday, but some of those players we've only been able to look at for an hour-and-a-half in training and then 45 minutes in a friendly. It's not enough for us to be making that call yet, so we need to see more.
"I still want to bring in another forward and I still need another option on the right-hand side. And, although we have plenty of options at the back, a couple of the displays from those trialists may mean that we add another player in that area of the pitch as well."
Weaver is reluctant to reveal the identities of those currently on trial with the Sulphurites until he has had the chance to tie up any deals he may wish to do to secure the players' services for the upcoming campaign.
Among those currently on trial at the club are a right-sided defender with a Premier League background, a versatile attacking player who has played in both the Football League and National League in recent seasons and a winger who came through the ranks at a top-flight club.
Town's clash with Championship Huddersfield, their third fixture of pre-season, kicks-off at the EnviroVent Stadium at noon on Saturday.