Notorious paedophile Gerald Ridsdale molested an 11-year-old girl in the home he once shared with other priests, including now Cardinal George Pell, an inquiry into child sexual abuse has been told.

Ridsdale, an 81-year-old former priest, was back in the witness box for a second day at the Royal Commission into Institutional Responses to Child Sexual Abuse in Ballarat.

The inquiry heard the defrocked priest abused the girl at the Ballarat East presbytery in the 1970s, where he was living with a number of other priests, including Australia's now most senior Catholic leader.

The inquiry heard the girl went to look at the rock collection in Ridsdale's bedroom, but saw a pornographic magazine and ran away.

When Ridsdale caught up to her, he raped her.

Court documents read out at the inquiry revealed the girl believed another priest was there and heard her being assaulted, but did not intervene.

Ridsdale told the hearing that was probably true, but could not remember who it was.

"I have no idea about the priests who were with me in Ballarat East," he said.

Ridsdale did say he could recall Cardinal Pell was living at the parish at the time.

"I have to accept that fact that George Pell was there but I don't remember any of the others," he said.

Cardinal Pell has told the royal commission he is willing to appear in person and give evidence.

Ridsdale's lack of memory about events slammed as 'incredible'

Ridsdale had earlier told the commission he could not remember many details about his past, including the Catholic Church's knowledge of his offending against numerous children in regional Victoria.

It led the judge presiding over the inquiry to say that it was "incredible" he could not recall those details.

At one stage, Justice Peter McClellan expressed incredulity Ridsdale could not remember details of his offending, or which members of the Catholic clergy may have known about his abusive nature.

"Isn't it incredible?" Justice McClellan put to Ridsdale, after Ridsdale said he couldn't "remember anything about Mortlake" in western Victoria, where he abused many children.

Justice McClellan also expressed frustration about Ridsdale's inability to recall discussions with Bishop Ronald Mulkearns, who moved Ridsdale around western Victoria.

At one point, Ridsdale also appeared to backtrack on whether he was in fear of losing his priesthood.

"It's not a case of thinking you could've been," Justice McClellan told Ridsdale.

"You would've been absolutely terrified the Bishop was going to throw you out of the church."

Ridsdale replied: "I can only tell you what I remember."

At least three clergy members knew of Ridsdale's offending

Earlier, Ridsdale responded with, "I don't know ... I can't recall", when asked by counsel assisting, Gail Furncess SC, if Cardinal Pell ever spoke to Ridsdale about his offending, or whether Ridsdale ever told him about his problems with children.

Gerald Ridsdale (left) says he raped an 11yo girl at a home he shared with other priests, including George Pell (right). ( ABC News )

He also acknowledged at least three members of the clergy, including Bishop Mulkearns, knew of his prolific offending at Mortlake.

Ridsdale was also asked about his offending in New South Wales, after he was moved there from Victoria because he had "certain sexual problems".

He told the commission he abused children at several locations, including in his "underground house" at White Cliffs.

The inquiry heard one family who had been visiting Ridsdale for decades in prison did not know he had abused their own son.

Judge questions whether Ridsdale was 'coached'

Justice McClellan also raised the possibility Ridsdale may have been coached in what to say in evidence, asking him repeatedly who had visited him in prison in recent months, including on the March 17.

"You appreciate there'll be a record of people who've been to see you in jail, don't you?" Justice McClellan put to Ridsdale.

Ridsdale said he made regular phone calls to his sisters and had been visited by Father John McKinnon, of a western Victorian parish.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 5 minutes 7 seconds 5 m Hamish Fitzsimmons reports on the hearings.

He also backtracked on evidence that it was his barrister who approached Cardinal Pell to support him in court during the 1990s.

On Wednesday, Ridsdale said Cardinal Pell may not have known the nature of the child abuse charges against him, he did not know exactly what Cardinal Pell was going to say in his support, and that it was insignificant anyway.

He told the royal commission he barely knew Cardinal Pell.

But on Thursday he acknowledged, on the face of evidence put to him by Ms Furness, that he had approached Pell himself.

"It looks like I must've done that, yes," Ridsdale said.

Ridsdale has finished giving evidence to the inquiry but has not been formally excused as he could be recalled later for Church cross-examination.

The hearing continues.