Refer to figure.
At the top of the approach chart, you can find the various ATC frequencies for Aberdeen. The question states that the pilot recently switched from approach to tower and then needs to make the distress call. This call would normally be made on the frequency in use because:

• You are already working with a controller
• Increases the controller's situational awareness
• Increases the situational awareness of surrounding traffic on the same frequency

The attached figure shows the frequency for Aberdeen Tower to 118.1 (shown in the red box)

ICAO Annex 10, Volume II

5.3.2 Radiotelephony distress communications

5.3.2.1 Action by the aircraft in distress 5.3.2.1.1 In addition to being preceded by the radiotelephony distress signal MAYDAY (see 5.3.1.2), preferably spoken three times, the distress message to be sent by an aircraft in distress shall:

a) be on the air-ground frequency in use at the time;
b) consist of as many as possible of the following elements spoken distinctly and, if possible, in the following order:

1) name of the station addressed (time and circumstances permitting);
2) the identification of the aircraft;
3) the nature of the distress condition;
4) intention of the person in command;
5) present position, level (i.e. flight level, altitude, etc., as appropriate) and heading.