$ sigtool --test-sigs manual/sigs.ldb build/test.exe
VIRUS NAME: Test.Sig.LDB_1of2_PE_ICON_1
TDB: Engine:51-255,Target:1,IconGroup1:TEST_ICON_GROUP_1
LOGICAL EXPRESSION: 0
 * SUBSIG ID 0
 +-> OFFSET: ANY
 +-> SIGMOD: NONE
 +-> SUBSIG: 434c414d41565f544553545f5052494e54465f535452494e475f
MATCH: ** YES/CHECK OFFSET ** (50 matches at offsets: 1173430 1173380 1160786 1160736 1113386 1113336 1065986 1065936 1018586 1018536 971186 971136 923786 923736 876386 876336 828986 828936 781586 781536 734186 734136 686786 686736 639386 639336 591986 591936 544586 544536 497186 497136 449786 449736 402386 402336 354986 354936 307586 307536 260186 260136 212786 212736 165386 165336 117986 117936 70586 70536)

You'll need to put the full definition of the sigs you want to search for in their own clamav database file with the correct file extension (like sigs.ldb in the example above for an LDB sig).  You can find the full definition of a signature in the ClamAV database via sigtool using sigtool --find-sigs.  For example:

sigtool --find-sigs=Win.Dropper.Ramnit-8009875-1
[daily.ldb] Win.Dropper.Ramnit-8009875-1;Engine:51-255,Target:1;0&1&2&3&4;6f754d4e7539;5c2d52445e6d;7a4f6e4f4530;413759616320;50285e38283420

In that example, you would put Win.Dropper.Ramnit-8009875-1;Engine:51-255,Target:1;0&1&2&3&4;6f754d4e7539;5c2d52445e6d;7a4f6e4f4530;413759616320;50285e38283420 into sigs.ldb and then pass that as the argument to sigtool --test-sigs along with the matching sample path.

There are some known issues with sigtool --test-sigs, but hopefully it works well enough for your use case

Hope that helps!

-Andrew