Rudolph became the seventh target of Spears's ex-husband Kevin Federline.
Court documents released Thursday revealed Federline's team has also served – or intends to serve – her "sober companion" and a former nanny, her assistant, a former bodyguard, a former assistant and records at Promises rehab center.
The heavily redacted documents also disclosed Spears's income: $737,868 a month.
Federline receives $20,000 a month in spousal support and "has no net income after business expenses," the papers say. The payments end in November Spears is "clearly the 'monied party'" in the dispute and should pay $50,000 for her ex-husband's litigation expenses, Federline's lawyer, Mark Vincent Kaplan, argues in the papers.
Rudolph was served Thursday afternoon, said Erin Tietsort, the assistant manager at the Sunset Tan (of reality show fame) in West Los Angeles. "He's employed here. He's part-owner," she said.
Tietsort described the process server as a 5'8" brunette in black slacks and a buttoned-up shirt.
"We asked her who she was but she just said she had a meeting with [Rudolph]. After he walked in he said, 'Can I help you?' and she just handed the papers and left. He had no idea. He then said [to himself], "Oh, okay. Yeah. They've been looking for me. This is for Britney Spears-Kevin Federline.' I was like, 'Really?' And he just stared out the window. You could tell he wasn't too happy about it," said Tietsort.
Rudolph had tried to not get served because he felt his testimony under oath could hurt Spears's case, Ryan Seacrest – who was in contact with Rudolph over the weekend – said Monday.
"He's actually on the run," Seacrest reported. "After all they have been through he is still loyal to her."
Rudolph, whose subpoenaing was first reported by PerezHilton.com, is just the latest person handed a summons to appear in court in the pop star's fight with ex-husband.
Denise Truscello / WireImage
Kaplan, is behind the subpoenas, which will be used to compel those close to Spears to discuss her parenting style. The custody battle over Sean Preston, 23 months, and Jayden James, 11 months, began on Aug. 8, when Kaplan filed for primary physical custody.
Also Thursday, rapper T-Pain came out in support of the singer and says working with Spears was so professional that the two of them were able to record three songs in a short amount of time.
"She came in there, shook my hand and went right into the booth," T-Pain tells MTV News. "She was smiling the whole time. In an hour we had a song. ... She was about her business."
The rapper was equally impressed with her talent: "I sang it first and she sung over what I did ... in key and everything!"
T-Pain is slated to appear on the MTV Video Music Awards, which Spears is reportedly working on a performance for with magician Criss Angel.
Reporting by EUNICE OH