Question: What episode of "How I Met Your Mother" had the American musician Keith Konrad Slettedahl and had the lowest recorded viewership for season one?

Context paragraphs:
Harley Gaber: Harley Gaber (June 5, 1943 – June 16, 2011) was a visual artist and composer known for his minimalist and spectral approaches to time and sound.  With his emphasis on quiet sustained sonorities and textures, Gaber is counted among the early American minimalist composers, and considered to be a forerunner of drone and spectralism.  His best known recorded composition, "The Winds Rise in the North," has been called by musician Keith Fullerton Whitman "one of the holy grails of minimalism in music in the 20th century."

Keith Slettedahl: Keith Konrad Slettedahl (born August 9, 1973) is an American musician.  He is the singer and songwriter for Los Angeles pop rock group The 88.  In 2006, he appeared in the episode "Best Prom Ever" on the sitcom "How I Met Your Mother", playing a gig with his band on a High School-Prom.

Follow the Leader (Lost): "Follow the Leader" is the 15th television episode of the fifth season of ABC's "Lost".  The 101st episode of the show overall, "Follow the Leader" aired on May 6, 2009, on ABC in the United States.  The episode was written by supervising producer Paul Zbyszewski and co-executive producer Elizabeth Sarnoff and directed by Stephen Williams.  This episode marks the lowest recorded audience for Lost.

List of Dollhouse episodes: "Dollhouse" is an American science fiction television series created by Joss Whedon which premiered on Fox on February 13, 2009 in the United States.  It ran for two seasons before its cancellation, ending its run January 29, 2010.  The series comprises 27 produced episodes, with two unaired episodes – the original unaired pilot episode, "Echo" and the season one coda, "Epitaph One", which was aired internationally.  Both episodes were made available on the season one DVD and Blu-ray releases.

Multiples (album): Multiples is a studio album by American electronic musician Keith Fullerton Whitman, released on Kranky in 2005.

Internet Icon: Internet Icon is an online video-making talent competition (described as ""American Idol"-esque") that premiered on the YOMYOMF YouTube channel on June 12, 2012.  The show is a competition between groups to see who can be "the next internet icon" or be able to run their own YouTube channel while sustaining an audience.  "Internet Icon" was hosted by Chester See in season one and Chris Riedell in season two, and judged mainly by Ryan Higa and Christine Lakin in season one, with the addition of Timothy DeLaGhetto in the second season.  Nick Riedell was also included as a mentor of the contestants in the second season.  Additionally, there is also a guest judge who appears on the show each elimination episode.  The contestants complete challenges at the Los Angeles Center Studios, where the show is also shot.  The series is one of YOMYOMF's most popular.  After two seasons, "Internet Icon" was cancelled, due to funding issues.

Famous Places: Famous Places is the third album of American ambient musician Keith Kenniff under the Goldmund moniker.  Famous Places features piano compositions named after locations that have played an important part in Kenniff's life to date.  A close-miced recording technique accentuates the simplicity and intimacy of Kenniff's melodious musings, and while the piano solo is clearly the medium the Goldmund project is predominantly concerned with, Kenniff frequently adds contextual details to his recordings, setting his keywork among billowy, abstract drones, a few quietly mixed-in additional instruments and occasional percussion (such as 'Dane Street').

Chuck Versus the Cliffhanger: "Chuck Versus the Cliffhanger" is the fourth season finale of the American NBC action-comedy television series "Chuck".  Aired on May 16, 2011, it is the season's 24th episode, and the 78th overall episode of the series.  The episode was directed by Robert Duncan McNeill and written by series co-creator Chris Fedak, along with Nicholas Wootton.  Despite the episode's eponymous cliffhanger ending, supposedly leading into a fifth season, it was anticipated that "Chuck" would be cancelled after the fourth season for declining viewership, making "Chuck Versus the Cliffhanger" the "de facto" series finale.  However, a fifth and final season was ordered on May 13, 2011.

24: Legacy: 24: Legacy is an American television series created by Manny Coto and Evan Katz that aired on Fox network from February 5 to April 17, 2017.  The series is a spin-off of "24" which was created by Joel Surnow and Robert Cochran and its premiere served as the lead-out program for Super Bowl LI before moving to its regular time slot of Monday at 8:00 p.m.  The series' premiere was watched by 17.6 million people, the lowest post-Super Bowl program viewership since 2003's "Alias" but the most viewed episode in the franchise's history.

Best Prom Ever: "Best Prom Ever" is the 20th episode in the first season of the television series "How I Met Your Mother".  It originally aired in the United States on May 1, 2006.  It had the lowest recorded viewership for season 1 (7.24 million).

Supporting paragraphs: Keith Slettedahl Best Prom Ever
Answer: Best Prom Ever