When you initially configure your ADS-B "OUT" source, that is where ATC expects to receive if you have 1090 or 978 IN. All ADS-B "OUT" sources (1090 or 978UAT) will need this configuration setup. To configure this information for the Xponder 261/262 see Pg 11-22 of the SkyView Installation Guide, Rev-Z, V15.
Remember, 978UAT isn't part of ICAO, only within the USA.
FWIW: I have flown, and fly, a lot outside the USA and file ICAO flight plans often. The AIM dated 12/10/2015 on pages 5-1-21 and 5-1-22 has the requirements for the equipment codes for section 10 of the ICAO flight plan form. Your SkyView system is actually irrelevant for ICAO equipment code flight plan filing. Now, other equipment that may or may not be in your aircraft can and do make a difference.
Common equipment codes for our aircraft:
VOR/LOC/GS receiver with VHF comm = S
IFR GPS = G
8.33Khz comm radio = Y
Common Surveillance equipment examples:
1090 Transponder, no altitude reporting = A
1090 Transponder, with altitude reporting = C
1090ES Transponder, Mode S, ADS-B, Altitude = E
ADS-B Enhancement with SkyView:
1090 ADS-B "OUT" = B1
1090 ADS-B "OUT/IN" = B2
UAT ADS-B "OUT" = U1
UAT ADS-B "OUT/IN" = U2
So an aircraft with a SkyView system doesn't necessarily change anything with the codes. Here are some common examples, all with SkyView panel:
AC #1
Regular Comm Radio (KX-155A)
VOR/LOC/GS receiver (KX-155A)
Regular Mode C transponder (KT76C)
You file S/C
AC #2
Comm Radio with 8.33Khz capability (Dynon Comm Radio)
VOR/LOC/GS Receiver (VAL-INS-429)
Regular Mode C transponder (KT76C)
You file S,Y/C
AC #3
Comm Radio with 8.33Khz capability (Dynon Comm Radio)
Nav/Com IFR GPS Navigation (G430W)
Regular Mode C transponder (KT-76A)
S,Y,G/C
AC #4
Comm Radio with 8.33Khz capability (Dynon Comm Radio)
Nav/Com IFR GPS Navigation (G430W)
1090ES transponder with ADS-B "OUT" (SV-261)
S,Y,G/E,B1
Note that having a SkyView system doesn't make a difference in filing just what "other" equipment you may have in your aircraft.
REF:
https://www.faa.gov/air_traffic/publications/media/aim.pdf