The former US Open winner Raducanu personally had a strong week in Malaga and won all three matches without losing a set.
The 22-year-old said it was a “strange feeling” to go from the high of the semi-final victory to the team's agonizing defeat, but added that she would “take positives from her performances” after a two-month break due to a foot injury.
“I couldn’t be more proud of Katie and the way she fought,” Raducanu said.
“I think that really makes me believe that we can win this tournament.
“We were close. We have a great team and that definitely makes me want to try out my doubles even more.”
Despite the disappointment, Boulter said she was “proud” after giving everything to secure a place in the final against Italy.
Keothavong, whose side came into the 12-nation finals as the second-worst team, added: “I'm so proud of the way Katie led the team as number one.”
“She came up just a little short today, but she has a lot of fire in her belly.”
